Process and gas generator for generating fuel gas

ABSTRACT

A process and gas generator is disclosed for generating by dry distillation of solids and gasification of solids, a fuel gas substantially free of condensable dry distillation volatiles which would interfere with the intended use of the gas, e.g. for powering an internal combustion engine. 
     To achieve this, solids beds in distinct dry distillation and gasification zones are maintained under conditions favouring thermal cracking of condensable (tar) volatiles in the hot regions of both zones. For optimal control of these conditions these zones are physically separated by internals within a single reactor vessel and optionally by performing part of the dry distillation (pyrolysis) in a separate reactor vessel, in which case pyrolysis volatiles are fed in counter-current to the dry distillation bed, withdrawn from the top thereof and fed into and through the embers bed of the gasification zone. Thermal cracking of pyrolysis volatiles is prolonged and intensified by the manner in which these volatiles are conducted in intimate contact through the embers bed of the gasification zone in co-current therewith. The embers bed is guided along a progressively constricting pathway, which controls the rate of travel of and the period of residence of the solids bed in the process and generator.

FIELD OF THE INVENTION

The invention relates to a process for generating fuel gas by drydistillation of solids and subsequent gasification of solids. Theinvention also relates to a gas generator suitable for performing theprocess.

BACKGROUND OF THE INVENTION

The invention is based on the following state of the art:

The invention starts from a process such as may, for example, beperformed using a gas processor as described in DE 33 12 863 C2. In thatprocess the solid matter to be processed which contains gasifiableorganic material, passes under the action of gravity through a pyrolysischamber in which initially—in the absence of air—these solids arethermally subjected to dry distillation at a temperature of about 500°C. and are subsequently gasified for fuel gas generation by the additionof gasification medium at a temperature of about 800° C. Thegasification media are introduced substoichiometrically in relation tothe oxidisable material content. The organic solids which are fed intothe upper region of the pyrolysis chamber form in the gas processor aparticulate solids bed, which is supported by a material lock elementwhich limits the pyrolysis chamber at its lower end. In the region ofthe material lock element passages are provided for the fuel gasgenerated in the pyrolysis chamber. The residual material as well, whichremains after the conversion of the organic solids in the particulatesolids bed, emerges through the passages downwardly from the pyrolysischamber. The material lock element is movable and promotes, acting as adischarge element, the discharge of the residues from the particulatesolid bed. The gasifying media, air and/or steam, which are introducedinto the particulate solids bed in substoichiometrical ratio, passthrough the particulate solids bed in the direction of gravity,something which is attained by the maintenance of a pressure gradientbetween the feed locality of the gasification media into the pyrolysischamber and the outlet for the fuel gas at the passages associated withthe discharge element. Accordingly, dry distillation volatiles andgasification media as well as the fuel gas generated in the pyrolysischamber pass through the gas processor in co-current.

Using this flow mode, the dry distillation volatiles generated in thedry distillation zone of the particulate solids bed during drydistillation of the organic solids are passed through the gasificationzone following downstream in the pyrolysis chamber such that part of thepyrolysis volatiles react with the gasification media and are combusted.In the region of the discharge element there is formed accordingly anembers bed. It is a feature of the gas processor known from DE 33 12 863C2 that the dry distillation volatiles while passing through the embersbed are cracked: the tarry long-chain hydrocarbon components and othercondensable compounds of the dry distillation volatiles are convertedinto non-condensable short-chain hydrocarbon and other low molecularweight compounds. A high-quality fuel gas is thus formed which can beutilised not only by being combusted and used as heating gas in heatexchangers for heat generation, but it can also be used as a fuel forthe operation of internal combustion engines.

Dry distillation, also known as low temperature carbonisation, is aprocess, wherein carbonaceous solids, such as wood, but also wastematerials such as old tyres and plastic wastes are heated totemperatures at which the solids are decomposed to release a variety ofvolatiles and to usually leave behind a carbonised residue such as cokeor charcoal.

It is a problem in the process of the afore described type that insidethe particulate solid bed, where lumps of varying sizes occur of theorganic material to be processed, no homogeneous solids density can beattained as a result of which the reduced pressure in the combustionchamber below the discharge element for the withdrawal of the gases willnot result in a constantly maintained pressure gradient within theparticulate solids bed. In such regions within the particulate solidsbed, in which material bridges and cavities are formed, faulty reactionsand undesired flame breakthrough may occur, even in a direction oppositeto the set up co-current direction. Likewise, an inadequate conversionof the dry distillation volatiles may occur in the embers bed wherebythe quality of the fuel gases generated is compromised by drydistillation volatiles inadequately cracked in the embers bed beingdrawn off prematurely. Frequently the setting up of optimal parametersfor the gasification process and for the conversion of dry distillationvolatiles in the embers bed results in undesirable conditions in theparticulate solids bed of the dry distillation zone and vice versa, suchthat the control of the gas processor is unstable.

The structure of the particulate solids bed and the dry distillationattained in the particulate solids bed, degassing and gasification aredependent on the solids to be converted, their properties andgeometrical configurations, in particular their homogeneity and sizing.If an optimised gas generation is to be attained, the gas generator mustin each situation be adapted to these material properties andgeometrical configurations. For attaining a high fuel gas quality, thedimensions and the design of the gas generator are, therefore, alsocrucial. This applies particularly in the context of channelling in theparticulate solids bed. Whether such particulate solids channelling hasa negative effect also on the conversion of the solids and on the fuelgas quality attained in the gas processor will, however, also depend onthe technical design and construction of the pyrolysis chamber. It isknown to provide in the pyrolysis chamber agitation elements, whichbreak up channelling formed in the particulate solids bed whenever theyoccur, in which context reference is made, for example, to DE 197 55 700A1.

From DE 30 49 250 C2 it is known to convert the input material in twostages. The material is initially dried and devolatilised in a rotarydrum and thereafter the fuel gas is generated in a gasification shaftreactor downstream of the rotary drum. In this context a separation ofthe solids may be performed where the devolatilised material exits fromthe rotary drum so that only part of the material, i.e. the materialwhich has been carbonised in the rotary drum is introduced into thegasification shaft reactor. Components of the solid feed materials whichare unsuitable for gasification, are separately discharged before theycan enter the gasification shaft reactor. In order to dry anddevolatilise the material, the exterior wall of the rotary drum isheated, drying and devolatilisation being performed in the absence ofair. The gases thereby formed are withdrawn from the rotary drum in theconveyance direction of the material in co-current It is a disadvantagethat the thermal conditions for the formation of dry distillationvolatiles are not adequately adaptable dynamically to the conversion inthe gasification shaft reactor. The required control of the processorreacts too slowly when adaptations are necessary to the materialconversions taking place and, more particularly, the gas processor isadaptable to different qualities of available materials for processingonly at high cost.

A need has been recognised to provide a process and a gas generatoradaptable in a simple manner to whatever solids must be processed. Onthe one hand, the solids are to form within the gas generator aparticulate solids bed which is optimised for the fuel generation andwithin which an adequate dry distillation of the material can beattained. On the other hand, the high molecular weight hydrocarbon andother compounds in the dry distillation volatiles should be cracked ascompletely as possible in the gas processor. Dry distillation andgasification should be adaptable to one another in an optimised mannerdepending on the material to be processed. For that purpose it has nowbeen recognised in accordance with the invention that more effective andmore reliable intimate contact needs to be achieved for an adequateduration within an appropriately set up temperature range to ensureadequate and substantially complete cracking of all condensablevolatiles which otherwise interfere with the satisfactory operation ofinternal combustion engines and which can even interfere with theoperation of sensitive burner nozzles.

It is, moreover, the intention that the gas generator, even after havingbeen taken into operation, should be adaptable and dimensionable withrelatively little effort in accordance with data which are establishedempirically only during actual operation.

Particular needs have been recognised for a fuel gas generator processand apparatus that is on the one hand readily adaptable on the spot tochanging circumstances and is on the other hand fully self-sufficientand therefore suitable for being used as a decentralised power source,capable of being operated independently of whether or not a power gridis available.

These needs are even more pressing in remote and underdeveloped regionsinter alia in the following respects and to fill the following needs:

-   ability to utilise all kinds of available combustible materials    (gasifiable and/or dry-distillable);-   seasonal variations of these supplies;-   wastes which need to be disposed of;-   energy needs: mechanical, electrical and thermal energy and    fluctuations of these needs;-   alternative uses of the products of dry distillation and/or    gasification.

SUMMARY OF THE INVENTION

These objects are attainable in a process of the genus referred to inthe introduction according to the invention which may be defined as aprocess for the generation of a fuel gas by dry distillation ofcarbonaceous solids in a dry distillation zone into which thecarbonaceous solids are fed via a solids supply and in which the solidsare heated, where applicable dried and are dry-distilled with theliberation of dry distillation volatiles and, by further conversion ofthose volatiles in a gasification zone in the presence of carbonaceoussolids passing through the gasification zone at least in part undergravity in the form of a bed of particulate solids, to whichgasification media are fed in substoichiomentric quantities, the drydistillation volatiles withdrawn from the dry distillation zone enteringthe gasification zone and flowing through the bed of particulate solidsbeing there maintained in co-current with the direction of travel of thelatter, an embers bed being formed by the bed of particulate solids inthe terminal portion of the gasification zone in the region of adischarge element for substantially fully gasified material, throughwhich embers bed the gas formed in the bed of particulate solids passes,whereby condensable volatiles components contained in the gas arecracked, and wherein the fuel gas so generated is withdrawn from thelower region of the bed of particulate solids of the gasification zone.

The generic type of the apparatus for performing such a process may bedefined as a gas generator for generating a fuel gas, including a solidsfeeder, discharging into a dry distillation zone, wherein solidsintroduced by the solids feeder are heated, dried if necessary, andsubjected to dry distillation thereby to release dry distillationvolatiles downstream of the dry distillation zone into a gasificationzone supplied with and containing a bed of gasifiable carbonaceoussolids, supported on a fire grate device restricting the rate ofdownward movement of the solids of the bed under gravity, in co-currentwith dry distillation volatiles released from the dry distillation zoneflowing through the bed of gasifiable carbonaceous solids, a supply ofoxygen-bearing gas in the dry distillation zone supporting partialcombustion for heating the dry distillation zone and a supply ofgasification medium maintaining gasification conditions in thegasification zone, at least the lower region of the bed of gasifiablecarbonaceous solids being maintained in an embers bed condition throughwhich the dry distillation volatiles and volatilised products ofgasification pass in order to be subjected to thermal cracking.

In accordance with a first aspect thereof the present invention providesa process for the generation of a fuel gas by dry distillation ofcarbonaceous solids in a dry distillation zone into which thecarbonaceous solids are fed via a solids supply and in which the solidsare heated, where applicable dried and are dry-distilled with theliberation of dry distillation volatiles and, by further conversion ofthose volatiles in a gasification zone in the presence of carbonaceoussolids passing through the gasification zone at least in part undergravity in the form of a bed of particulate solids, to whichgasification media are fed in substoichiometric quantities, the drydistillation volatiles withdrawn from the dry distillation zone enteringthe gasification zone and flowing through the bed of particulate solidsbeing there maintained in co-current with the direction of travel of thelatter, an embers bed being formed by the bed of particulate solids inthe terminal portion of the gasification zone in the region of a firegrate element acting further as a solids discharge element for theresidual solids after completion of the gasification, through whichembers bed the gas formed in the bed of particulate solids passes,whereby condensable volatiles components contained in the gas arecracked, and wherein the fuel gas so generated is withdrawn from thelower region of the bed of particulate solids of the gasification zone,wherein gas containing oxygen is introduced into the dry distillationzone in substoichiometric amount for generating heat by partialcombustion of the solids to be dry-distilled passing through the drydistillation zone in the form of a bed of particulate solids under theaction of gravity before the generated fuel gas product is separatedfrom ashes and any cinders and is withdrawn and forwarded for furtheruse, said process further comprising additional measures for furtherdecreasing the content of condensable dry distillation volatiles in thefuel gas product-by increasing the intimate contact of the gases andvapours with the solids beds through which they pass, selected fromeither or both of the following:

-   -   A) that the embers bed of the gasification zone is conducted        from the higher lying regions of said zone under gravity towards        and through a constricted lower peripheral passage region of the        gasification zone defined between the outer periphery of the        fire grate element and the inner periphery of exterior walls of        a reactor in which the process is performed, and in co-current        therewith the dry distillation volatiles and gasification gases        and any gaseous cracking products are passed in intimate contact        with and through the embers bed and from there travels down a        funnel-shaped constricting pathway below the fire grate element        leading into and ending with the ash withdrawal region, where        the separation occurs between the ashes and any cinders and the        generated fuel gas product;    -   B) that in at least one dry distillation zone in the form of a        bed of particulate solids under the action of gravity the gas        present in that zone passes through the solids in        counter-current to the direction of travel of the solids to be        dry distilled, the solids thereby being dry distilled and the        dry distillation volatiles thereby formed in the dry        distillation zone being withdrawn from the dry distillation zone        near the solids supply region and that at least part of the dry        distillation volatiles formed in the dry distillation zone        withdrawn from near the solids supply region feeding the dry        distillation zone with carbonaceous solids are from there        forwarded into the gasification zone, where they, together with        gasification gases and any gaseous cracking products, pass in        co-current with and in intimate contact with and through the        embers bed of the gasification zone and are subjected to        cracking of condensable volatiles, before being separated from        ashes and any cinders and being withdrawn as a fuel gas product.

According to a second aspect of the invention there is provided a gasgenerator suitable for performing the process according to the inventionfor generating a fuel gas product, which is of the genus includingsolids feeder means discharging into a solids supply portion of a drydistillation zone, in which dry distillation zone solids introduced bythe solids feeder means are heated, dried if necessary and subjected todry distillation, thereby to release dry distillation volatiles into agasification zone supplied with and containing a bed of gasifiablecarbonaceous solids downstream of the dry distillation zone andsupported on a fire grate device, restricting the rate of downwardmovement of the solids of the bed under gravity in co-current with drydistillation volatiles released from the dry distillation zone as wellas the gasification media and the generated fuel gas in the gasificationzone flowing through the particulate solids bed, a supply ofoxygen-bearing gases in the dry distillation zone supporting partialcombustion therein for heating the dry distillation zone and a supply ofgasification medium being provided for maintaining gasificationconditions in the gasification zone by the provision of feed lines forgasification media to be introduced into the particulate solids bedwhich enter into the gasification zone, at least the lower region of thebed of gasifiable carbonaceous solids being maintained in an embers bedcondition through which the dry distillation volatiles and volatilisedproducts of gasification pass in order to be subjected to thermalcracking and including an ash withdrawal region including a gasseparation zone and discharge passage for the generated fuel gasproduct.

In accordance with the invention the apparatus provides additionalfeatures adapted for further decreasing the content of condensable drydistillation volatiles in the fuel gas product by increasing theintimate contact of the gases and vapours with the solids beds throughwhich they pass, selected from either or both of the following:

-   -   a) that in relation to higher lying regions of the gasification        zone the fire grate device, acting further as a discharge        element for the solids residues of the gasification, defines a        constricted peripheral passage for the embers bed of the        gasification zone between the outer periphery of the fire grate        device and the inner periphery of the exterior walls of the        gasification zone, which constricted peripheral passage merges        into a downwardly and inwardly funnel-like sloping constricting        pathway below the fire grate device leading into and ending with        the ash withdrawal region, where the separation occurs between        the ashes and any cinders and the generated fuel gas product;    -   b) that through at least one dry distillation zone solids to be        dry-distilled pass in the form of a particulate solids bed under        the action of gravity, wherein further a gasification medium        feed means for an oxygen-containing gas enters below the        particulate solids bed and wherein for the withdrawal from the        dry distillation zone of the dry distillation volatiles, formed        with heat generation by partial combustion of the solids in the        dry distillation reactor, a dry distillation gas duct is        connected in the region of the solids supply means and so enters        into a gasification zone, that the dry distillation gas flows        through the particulate solids bed in the gasification zone in        intimate contact with and in concurrent to the solids material.

From what follows it will become apparent to the person skilled in theart how to select from features A) and B) of the process and a) and b)of the apparatus that combination which is best suited to achieve theobject of decreasing the content of condensable dry distillationvolatiles in the product gas, depending on the materials and facilitiesavailable for the gasification.

This constricting pathway in the process (features A))as well as in theapparatus (features a)) serves to ensure that the embers bed in thelower region of the gasification zone is maintained in an idealcondition and configuration for intimate and prolonged contact betweenthe downwardly moving embers bed and the gases still containingcondensable dry distillation components which need to be removed bycracking at the high temperatures of the embers bed. The constrictingpathway makes allowance for the decrease in volume of the particulatesolids as they are being subjected to partial combustion andgasification reactions. At the same time the residence period of theembers bed before the discharge of the solids residues is prolonged toensure that these solids are converted to the maximum extent and thatthe solids residues discharged are composed mostly of ash with a minimumof cinders still containing combustible or gasifiable carbon.Restricting the rate of discharge of the solids residues also slows downthe gravitational descent of the upstream regions of the beds of solidsbeing converted in the process and generator and generally assists inmaintaining bed conditions favouring optimised conversion ofdry-distillable/carbonisable and/or gasifiable carbonaceous solids aswell as intimate contact with the gases passing trough the bed toachieve the desired conversion of undesirable high molecular weightcondensable volatiles into a fuel gas substantially composed of lowermolecular weight non-condensable gases and volatiles, i.e. moreeffectively than was possible in accordance with the prior art.

This controlled discharge of solids and intimate contact between solidsand fuel gas is further promoted by the meandering pathway through andout of the solids bed right up to the final separation of the gasdischarge from the solids being discharged. This feature will be furtherdealt with below.

Preferred embodiments provide that the fuel gas is withdrawn from theconstricted pathway and then passes in counter-current heat exchangewith gasification medium being fed into the gasification zone. Thisfeature contributes to the important thermal balance of the process. Itis important to conserve heat and employ it usefully in the process forthe dry distillation, gasification and thermal cracking processes, sinceexcessive heat losses have in the past made it difficult to maintain thetemperature conditions required for achieving a high quality fuel gas.

What takes place in the embers bed according to the aforegoing is to aconsiderable extent complemented by process conditions in the drydistillation zone, see item B) and item b). If these process conditionsare maintained such that the gas passing through the embers bed alreadyhas a relatively low content of condensable dry distillation volatiles,it becomes easier to remove any last traces thereof by cracking in thehigh temperature embers bed in the gasification zone. This can beachieved particularly effectively by certain preferred expedients of theprocess and apparatus.

In accordance therewith, gas containing oxygen is introduced insubstoichiometrical amount for the partial combustion of the solids intothe dry distillation zone in counter-current to the direction ofconveyance of the solids which pass through the dry distillation zone inthe form of a particulate solids bed under the action of gravity in sucha manner that the solids are subjected to dry distillation and that indoing so dry distillation volatiles formed in the dry distillation zoneare withdrawn from the dry distillation zone in the vicinity of thesolids feed, from there to be passed into the gasification zone. In thegasification zone, the dry distillation volatiles flow in co-current tothe carbonisable solids passing through the gasification zone. Inaccordance with the invention, due to the introduction ofoxygencontaining gases into the dry distillation zone in counter-currentto the direction of travel of the material to be converted and byreversing the gas flow in the gasification zone, through which the drydistillation volatiles flow in co-current to the carbonisable solids,the process of fuel gas generation is so split up that on the one hand,the dry distillation and on the other hand, the gasification arerendered separately controllable. The gas introduced into the drydistillation zone can be adjusted in respect of oxygen content andamount to the energy required for heating, drying and dry-distilling theorganic solids in order to generate dry distillation volatiles. In thecourse thereof the dry distillation volatiles whilst flowing through thebed of particulate solids in counter-current to the direction of travelof the solids to be converted, are purified by the partial removal ofhigh-boiling dry distillation volatiles which condense and are separatedin the cold material beds in the particulate solids bed. Thegasification zone following onto the dry distillation zone isindependent of the dry distillation process and independent of thesetting up of optimised dry distillation of the solids to the desiredquality of the fuel gas to be generated. For that purpose solid matter,which is essentially substantially carbonisable or has already beencarbonised is introduced into the gasification zone, non-gasifiablesolids components which interfere with the control of the gasificationprocess and the generation of high quality fuel gases are kept out ofthe gasification zone. In this manner, not only can the fuel gas qualitybe increased, but the constancy of the gas quality is also improved andmajor departures from optimal component contents in the fuel gas canalso be avoided.

Performing the gas flow in counter-current to the main direction oftravel of the particulate solids bed in the dry distillation zone offersimportant advantages as described more fully with reference to thedrawings. To do so whilst operating the gasification zone in co-current,may be performed very conveniently in two separate reactor vessels, afirst reactor vessel accommodating the dry distillation zone or a majorpart thereof and the second vessel accommodating the gasification zone.In that event, the first reactor vessel containing the dry distillationzone can be operated in such a manner that the solid carbonaceouscontent of the solids bed in the first reactor vessel is consumedentirely in the partial combustion, leaving behind, besides the drydistillation volatiles, only solids residues composed substantially ofash with little or no residual carbon. This is to be contrasted againstthe disclosure of DE 35 44 792 C2 where the solid residue of thedegasification taking place in the degasification shaft furnace isessentially coke which, according to the example, is cooled before beingcharged into the gasification furnace. Another advantage of performingthe process in two separate vessels resides in that the first reactorvessel can be charged with solids for dry distillation—even garbage orold motor vehicle tyres quite different from and in quantities largelyindependent of the solids charged into the second reactor vessel.However, again in contrast to the disclosure of DE 35 44 792 C2 theprocess, even with counter-current flow conditions in the drydistillation zone, may also be conducted in such a manner that thesolids leaving the dry distillation zone are in the form of a carbonisedembers bed which passes in that form directly into the gasificationzone. This embodiment can quite readily be performed in a single vessel,provided it offers such a bed height that the gas flows inside theparticulate solids bed can be split into an upward and a downwardstream. The upper portion of the bed representing the dry distillationzone will then be run with the gas flow passing upwards incounter-current with the bed solids. The lower portion representing thegasification zone is operated with the gas flow therein passingdownwards in co-current with the bed solids. The dry distillationvolatiles of the dry distillation zone will be withdrawn from the top ofthe dry distillation zone and be reintroduced into the vessel at a levelbelow the dry distillation zone in the gasification zone.

A further development of the inventive concept provides for theemployment of the generator fuel gas, at least in part, for operating agas motor or gas turbine generator unit for the generation of electricalenergy. Of substantial importance is the utilisation of part of theelectrical energy thereby generated for the electrolytic production ofhydrogen as an optionally storable source of energy, oxygen therebyformed being re-admixed to the oxygen-containing gas to be introducedinto the dry distillation zone and/or to the gasification medium to beintroduced into the gasification zone. In this manner, an at leastpartly closed loop gas circuit is formed for the manufacture of fuel gasfrom organic solids, allowing at the same time the feed ofnitrogen-containing air as required for the solids conversion to bereduced.

In order to act onto the particulate solids bed and for the continuousmovement of the solids particles in the particulate solids bed and theirintense mixing up the discharge element of the gasification reactor ispreferably designed in a particular manner in the gas generatoraccording to the invention. The discharge element is of conical or,preferably, pyramidal configuration, such that the cone or pyramid apexis upwardly directed opposed to the main direction of movement of thesolids passing through the particulate solids bed and the cone surfaceor the side faces of the pyramid serve as sliding areas for the solids.Whenever movement takes place of the discharge element, in particular byrotation of the shaft to which the discharge element has been fitted,the solids particles in the particulate solids bed are then continuouslymoved about and rearranged so that bridgings in the particulate solidsbed or channelling inclined to result in flame breakthrough between thesolids particles are broken up. The pyramidal design of the dischargeelements thus replaces material forwarding formations for the movementof the particle bed as is known, for example, from DE 197 55 700 A1.These known material advance members, in contrast to the pyramidalconfiguration of the discharge elements according to the invention, canbe moved in the particulate solids bed only with considerable force. Inaddition, the discharge elements according to the invention have asimple construction. It is of advantage to employ as discharge elementsa plurality of pyramidally designed fire grate elements, which, viewedin the direction of main advance of the solids, are arranged in theparticulate solids bed in succession at different levels and whichintensively rearrange the particulate solids bed at different levels.The formation of bridges and channelling in the particulate solids bedmay then be avoided to a very considerable extent if for each fire grateelement a different pyramidal configuration is selected, in particular,where each pyramid comprises a different polygonal plan view. In thesimplest case two fire grate elements are provided to serve as thedischarge element, one of the discharge elements having a square planview, whereas the other has a hexagonal pyramidal plan view area

Again many variations are possible. It will be understood that a conicalshape may be regarded as a pyramid having an infinite number of pyramidside faces. If a pure cone shape is found to be too smooth to effectadequate agitation, rearrangement or advancing action on the solids bed,it is possible to apply any desired number of ribs or other protrusionsor depressions to the cone surface. These may extend radially orobliquely, e.g. in a spiral pattern, the general rule being to achievethe desired effect on the bed with a minimum of force having to beexercised.

In an advantageous embodiment of the gas generator, a plurality ofsegments adapted to be connected up to one another in a gas-tight manneralong connecting planes extending essentially normal to the maindirection of movement of the solids to be converted, are provided forthe connection in each case of an adjoining segment, at least in orderto form the dry distillation and/or the gasification zone. Cavitiesrequired for the introduction or withdrawal of gases, in particular forthe introduction of gasifying medium into the particulate solids bed arethus provided in the region of the connecting planes between thesegments. This construction of the gas generator from individualsegments permits to adapt the generator to whatever conditions may berequired for an optimised conversion of the material to be dried,dry-distilled and to be gasified. If for dry distilling and, whereapplicable, prior drying of the solids, for example, longer periods ofresidence of the material are required in the dry distillation zone, itis possible to lengthen the particulate solids bed column in a simplemanner by the stacking on of further segments. Changing of thethroughput rate, once proved to be optimal in the gasification regionand in the embers bed, is thus not required. The dry distillation andgasification may thus be controlled independently from one another bymeans of the segment dimensions. The geometric particulars of thesegments in the actual direction need in this context not be uniformlydimensioned. The dimensions and design of the segments can be adapted tothe solids to be processed as required for an optimal dry distillationand gasification process. The segments are, in particular, adaptable tothe desired local regions for feeding the gasification means into theparticulate solids bed and to the required throughput of the solids.

It is advantageous to utilise the individual segments for theconfiguration of the generator interior. In order to avoid channellingin the particulate solids bed or to break up channelling which may haveformed, the segments, are preferably so dimensioned that in the maindirection of movement of the material in the particulate solids bedconstrictions are formed which constrict the cross-section of theparticulate solids bed and/or provide expanded regions of thecross-section of the particulate solids bed. Such constrictions andexpanded regions result in rearranging the solids during their passagethrough the dry distillation or gasification reactor. It may beadvantageous to introduce suitable devices for such rearranging alone orin addition, in particular, flaps which are fitted to the segments so asto be pivotal in the particulate solids bed and which can be used forthe localised rearrangements of the condition of the particulate solidsbed and, in particular, for loosening up and breaking up materialbridges which may have formed.

It is important to design the gas processor in such a manner that noflame breakthrough occurs in the particulate solids bed and thatchannelling which is inclined to lead to such flame breakrough can formonly to a lesser extent and for short times. For this purpose, flamebreakthrough obstructions and specially selected and dimensionedinternals in the segments may be used, in particular, the installationof rotary or rocking fire grates or flaps serving as discharge elementbelow the particulate solids beds in the dry distillation and/orgasification reactor. The design of such components depends on thenature of whatever material to be converted forms the particulate solidsbed, in the first instance the lump size and composition. As regards thedry distillation reactor, it must also be borne in mind that in certaincircumstances non dry-distillable solids residues need to be dischargedfrom the dry distillation reactor, for example, metal residues, ifplastics having metal wire inclusions are to be subjected to drydistillation. It also depends on the sizing of the solids in thegasification reactor, in which manner flame breakthrough obstructionsand internals acting as discharge elements need to be dimensioned inorder to attain in the gasification reactor a uniform throughput of drydistillation volatiles adapted to the desired generation of short-chainhydrocarbon and other non-condensable compounds and a correspondinglyhigh fuel gas quality. In order to optimise the gasification reactor, itis, in particular, necessary, to match two process procedures to oneanother: firstly, the extensive gasification of the solids fed into thegasification reactor, secondly, the cracking process in the embers bed.This primarily determines the quality of the fuel gas generated in thegas processor. The fuel gas generation may thus be optimally adapted tothe solids to be processed by the adaptation of specifically designedsegments of the gas generator. The dry distillation and gasificationzone may thus be regulated independently from one another in accordancewith whatever processes take place in the zones.

Of particular importance for this purpose is the design of the dischargeelement which supports the particulate solids bed and which dischargesunderneath the particulate solids bed the solids residues not convertedin the gasification reactor. The purpose of such a discharge element isto so control the discharge of residues and of generated fuel gas thatthe solids throughput is adapted to the temperature required in theembers bed and can be optimised to the amount and quality of the fuelgas generated. The residues are to be discharged in a particular degreeof fineness, there being prescribed a maximum particle size, and thedischarge of the residues and the withdrawal of the fuel gas generatedcan be controlled separately. Thus, provision may be made to so providea baffle formation in the discharge region for the discharge of solidsresidues that the solids discharge is limited to a maximum solidsparticle size and that for the fuel gas flowing out a gas passage isprovided which has the effect that the solids residues to be dischargedand the fuel gas being generated, can be withdrawn from the gasificationreactor separately. In order to adjust the maximum solids particle size,it is advantageous to fix the baffle formations to the bottom of adischarge element, the level of which is adjustable. Preferably, atleast one passage is provided for the free through-flow of the fuel gasbetween the bottom of the discharge element and the baffle formation.

In order to facilitate the controlled discharge of the solids residues,the baffle formation is preferably composed of a plurality of solidsguides which, viewed in the direction of discharge of the solidsresidues, follow each other successively. For the free throughput of thefuel gas this design provides for at least one through-flow passage inthe region of the last one of these solids guide means. Between thesolids guide means throughput advancing formations for the solidsresidues are mounted, which by turning over the solids in the dischargeregion and, where necessary, also by breaking up of agglomerations ofsolids particles accelerate the discharge. For moving the dischargeelement the discharge element is fitted to a rotatable drive shaft.

For the feeding of gas, in particular, gasification media or for thewithdrawal of fuel gas from the gasification reactor, provision is madefor the drive shaft by which the discharge element is subjected torotary movement to be designed as a hollow shaft. Advantageously, inparticular the generated fuel gas is withdrawn through the shaft in anupward direction from the gasification reactor. This is particularlyappropriate if the shaft is mounted in the overhead region of thegasification reactor.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention and further appropriate embodiments of the invention willin the following be further explained by way of working examples Thedrawings more specifically show in:

FIG. 1 a flow diagram of an embodiment of a process and apparatus forthe generation of fuel gas, using a first reactor vessel foraccommodating the dry distillation zone and a second reactor vessel foraccommodating the gasification zone.

FIGS. 2 and 3 represent flow diagrams of two further embodiments of aprocess and apparatus for the generator of fuel gas using a singlereactor vessel accommodating both the dry distillation zone as well asthe gasification zone.

FIG. 4 a longitudinal section of a dry distillation reactor according tosection line IV—IV according to FIG. 5,

FIG. 5 a cross-section through the dry distillation reactor according toFIG. 4 along section line V—V,

FIG. 6 a detailed view of a dry distillation reactor according to FIG. 4according to section line VI on a larger scale,

FIG. 7 a gasification reactor in axial longitudinal section

FIG. 8 a cross-section of the embodiment according to FIG. 7sectionalised along section line VIII—VIII,

FIG. 9 a cross-section of the embodiment according to FIG. 7sectionalised along section line IX—IX,

FIG. 10 a detailed view of a gasification reactor according to FIG. 7showing the rotary fire grate and cinders discharge region inlongitudinal section along section line X—X according to FIG. 11,

FIG. 11 a transverse section of the embodiment according to FIG. 10along section line XI—XI,

FIG. 12 a further embodiment of a gasification reactor having a centralfuel gas withdrawal duct,

FIG. 13 a detail of a gasification reactor according to FIG. 12 with therotary fire grate and cinders discharge region in longitudinal sectionaccording to section line XIII—XIll according to FIG. 14,

FIG. 14 a transverse section of the embodiment according to FIG. 13along section line XIV—XIV,

FIG. 15 a view similar to FIG. 7 of yet another embodiment of agasification reactor,

FIG. 16 a reverse plan view of portion XVI in FIG. 15,

FIG. 17 a detail view on a larger scale in vertical broken away sectionof a modification of the rotary fire grate and cinders/ash dischargeregion in FIG. 15,

FIG. 18 a reverse plan view of portion XVIII in FIG. 17,

FIG. 19 a plant for the generation of fuel gas and the production ofhydrogen.

DESCRIPTION OF SPECIFIC EMBODIMENTS

In FIG. 1 the process according to the invention is illustrated by wayof a flow sheet. The solids to be gasified having organic materialcontents, in the working example dry-distillable biomass such as, e.g.,waste wood, straw bales or even bio-garbage which is difficult to rot orplastics containing metal such as wastes from metal reinforcedinsulating materials or old tyres are introduced by way of a solids feed1 into a dry distillation reactor 2 and are there heated, dried therebyand subjected to dry distillation. The solids are heated in the drydistillation reactor by partial combustion of the organic materialcontents with the addition of gasification medium which, in relation tothe oxidisable solids content of the introduced solids, is added insubstoichiometrical amount The gasification medium flows by way of agasification means supply 3 into the dry distillation reactor 2.

The dry distillation volatiles formed in the dry distillation reactor 2by heating of the organic solids are withdrawn as a raw gas from the drydistillation reactor by way of a dry distillation volatiles line 4 andare transferred into a gasification reactor 5, charged with gasifiablematerial, in particular, carbonisable solids or coke or charcoal. Thegasifiable material for the gasification reactor must be suitablyselected for the gasification process to be conducted in thegasification reactor. The material as regards its gasificationproperties should be as homogeneous as possible and should be fed withan approximately uniform particle size as is the case, for example, withshredded wood or wood off-cut wastes, wood chemically still untreatedfrom carpentry workshops, shredded hedge or forestry wastes or nutshells, in particular, ground nut shells or olive pips. For purposes ofconversion of the introduced dry distillation volatiles, it is desirablethat the highest possible specific surface area should be offered to thevolatiles by the material in the gasification space. The gasifiablesolids are fed into the gasification reactor by way of a material lockdevice 6.

In addition to dry distillation volatiles, gasification media as wellare introduced into the gasification reactor 5. For that purpose agasification medium feed duct 7 is connected to the gasification reactor5. As is the case in the dry distillation reactor 2, the gasificationmedia are introduced in a substoichiometrical ratio to the oxidisablecontents of the gasifiable material such that combustion of a portion ofthe introduced solids also takes place in the gasification reactor 5.This causes the formation of an embers bed in the outlet region 8 of thegasification reactor. The fuel gas generated in the gasification reactor5 is drawn through the embers bed, for which purpose a fuel gas duct 9is connected to the gasification reactor. For the withdrawal of ash andnon-gasified solids residues an ash and cinders outlet 10 is provided.The material properties of the gasifiable materials fed into thegasification reactor are to be selected primarily with a view to theformation of this embers bed through which the fuel gas is to flow. Theembers bed must be of uniform structure, and, the more homogeneous thefeed material, the more homogeneous will be the embers bed obtained.Components in the material which would interfere with the homogeneity ofthe embers bed must be avoided. This applies, for example, to wireresidues in the material, but also to material components which attemperature above 800° C. in the embers bed are inclined to fuse such ase.g. silicates, which can agglomerate and bake together and which caninterfere with the desired optimal structure of the embers bed as wellas with the discharge of the ashes from the gasification space of thegasification reactor. In accordance with the process according to theinvention, such materials should not be introduced into the gasificationreactor 5 but into the dry distillation reactor 2 and will there servefor the generation of dry distillation volatiles which are thenintroduced as a raw gas into the gasification reactor there to beconverted into fuel gas.

For the utilisation of the generated fuel gas two alternatives areprovided in the working example according to FIG. 1. On the one hand, itis possible by combustion of compressed fuel gases in a gas motor or asin the working example in a gas turbine 11 which drives a generator 12,to generate electrical energy; on the other hand, a heat carrier may beheated by combustion of the fuel gas in a combustion chamber 13 with anair feed 14 and an appropriate heat exchange between hot combustion gasfrom the combustion chamber and a heat carrier in a heat exchanger 15downstream of the combustion chamber 13. The utilisation of thegenerated fuel gas can be controlled depending on energy requirements byway of a control valve 16 in the fuel gas duct 9. If water is convertedinto steam in the heat exchanger 15, as provided for in the workingexample by the connection of a water line 17 to the heat exchanger 15,the steam thus generated can also be fed as a working medium to a steamturbine 18 which serves for driving a generator 19.

In both utilisation alternatives the exhaust gas flows by way of anexhaust duct into the environment, thus from the gas turbine 11 by wayof an exhaust duct 20 a or from the heat exchanger 15 by way of anexhaust gas duct 20 b in which, if desired or required, waste gaspurification means may be employed.

Important features for the invention arm the gas pathways in the drydistillation reactor 2 and in the gasification reactor 5 as well as thesegmental construction of these two reactor.

The organic solids to be converted pass through the dry distillationreactor 2 as a particulate solids bed under the action of gravity in thedirection of gravity 21 from the top downwards. This direction ofmovement is denoted as the main direction of movement of the solids.During its movement through the solids particle bed the solids areheated, dried and dry-distilled. The not dry-distilled solids residuesare combusted. The ashes formed thereby and the non-combustible solidscomponents such as wire scraps emerge from the lower end of the drydistillation reactor at a discharge locality 22. In counter-current tothis direction of conveyance of the solids in the solids particle bed inthe direction of gravity 21, the dry distillation volatiles formed inthe dry distillation reactor pass through the dry distillation reactor2, being formed by heating the solids particle bed due to the combustionof part of the solids. In FIG. 1 the flow of the dry combustionvolatiles in the direction of flow 23 is denoted by broken lines. Thisdirection of flow 23 of the dry distillation volatiles in theparticulate solids bed is dictated by the feed 3 of gasification mediuminto the lower region of the dry distillation reactor and the withdrawalof dry distillation volatiles in its uppermost region by way of the drydistillation volatiles duct 4. The gasification media flowing in throughthe gasification media feed means 3 and resulting in the combustion ofpart of the solids permeate the solids particle bed from below in anupward direction. The combustion of the solids in the dry distillationreactor takes place predominantly in the lower portion of theparticulate solids bed above the withdrawal position 22 for thecombustion residue. The gases so heated and flowing through theparticulate solids bed heat up the organic solids to dry distillationtemperature, in the working example to about 750° C. The drydistillation volatiles formed are passed in the direction of flow 23upwards through the particulate solids bed and thereby flow through thecolder beds of particulate solids in the dry distillation reactor sothat higher boiling high molecular weight components in the drydistillation volatiles are at least partly separated off by condensationon the solids. As the cold particulate solids travel progressivelydownwards, these higher molecular weight dry distillation volatilescondensed thereon re-enter the regions where partial combustion of thesolids takes place. The condensed volatiles are thus subjected onceagain to relatively intense heat treatment whereby they are at least inpart combusted together with the solids and also subjected to a degreeof cracking: These effects contribute to the reduction of thecondensable volatiles content in the dry distillation gas.

In addition, the dry distillation volatiles may be withdrawnsubstantially ash- and dust free. Accordingly, a high quality drydistillation gas flows from the dry distillation reactor 2 as a raw gashaving a comparatively high content of low molecular weighthydrocarbons.

Non-condensed high molecular weight hydrocarbon contents and othercondensable volatiles such as phenols, amines, fatty acids, inparticular formic acid and alcohols, still present in the drydistillation gas are subsequently cracked when flowing through thegasification reactor 5 at high temperature, in the working example at atemperature between 950°/1050° C. in the embers bed in the dischargeregion 8 of the gasification reactor. As a result, a readily ignitablefuel gas mixture of high quality is generated in the gasificationreactor from the dry distillation volatiles jointly with the gases whichare formed by gasification of the feed materials to the gasificationreactor, e.g. coke or charcoal or shredded wood which itself gives riseto dry distillation volatiles besides gasification products.

In the gasification reactor the gasifiable material introduced by way ofthe material lock 6 as well as the dry distillation gas to be convertedand the gasification media flowing in by way of the gasification mediafeed line 7 are passed in co-current—in contrast to the counter-currentconditions in the dry distillation reactor 2—. In doing so the solidspass through the gasification reactor 5 as a particulate solids bed inthe direction of gravity 24 and the gases flow parallel thereto in thedirection of flow 25 through the interstitial open voids between thesolids particles of the solids particles bed. The flow path of the gasesin the gasification reactor 5 is diagrammatically indicated in FIG. 1 bydash-dotted lines.

Referring now to FIG. 2, the process according to FIG. 1 is herediagammatically shown to be performed in a single reactor vessel,including in its upper portion the dry distillation zone 2 a and in itslower portion the gasification zone 5 a, the approximate boundarybetween the two zones being indicated by a horizontal broken line. Allitems equivalent to items in FIG. 1 have the same reference numbers withan “a” added thereto. It will be seen that the feed of oxygen containinggasification medium 3 a, 7 a enters near the boundary between the twozones and serves both for partial combustion to provide the drydistillation in zone 2 a as well as for gasification in the thermalcracking zone 5 a. The dry distillation gases travel upwards in zone 2 ain counter-current to the solids la which travel downwards under gravity21 a, 24 a. The hottest region of the embers bed is denoted as 8 a. Thedry distillation volatiles are withdrawn by a gas extractor at the topof zone 2 a and returned into the gasification zone 5 a via duct 4 a.The fuel gas is withdrawn at 9 a and forwarded to any desired furtheruse as in FIG. 1.

Referring now to FIG. 3, all items equivalent to those in FIG. 1 and 2have the same reference numbers with a “b” added thereto. In thisembodiment The same oxygen-containing gas introduced at different levelsprovides partial combustion to achieve dry distillation in zone 2 b aswell as gasification in zone 5 b and a high temperature embers bed at 8b entering the constricting pathway between the side edges and undersideof a diamond-shaped discharge element and the funnel-shaped bottom ofthe reactor vessel 2 b, 5 b. All gas flows are downward in co-currentwith the solids in the direction of gravity 21 b. The fuel gas iswithdrawn at 9 b and passed to further use.

It is preferred to employ the indicated features of the gasificationzone 5 b, 8 b according to FIG. 3 also in the gasification zone 5 a, 8 aof FIG. 2 and in the gasification reactor vessel 5 of FIG. 1. Thesefeatures will be described more filly with reference to FIGS. 7 to 14.

A working example for the construction of the dry distillation reactor 2is illustrated in FIG. 4 and a working example for the gasificationreactor 5 is schematically shown in FIG. 7.

FIG. 4 shows a dry distillation reactor 2 having a reactor shaft 26 ofsquare cross-section. In FIG. 5 the dry distillation reactor is shown incross-section along sectional line V—V in FIG. 4. The solids to beconverted in the dry distillation reactor are fed into the drydistillation reactor by way of the solids feed means 1. The solids passin batches into the interior of the shaft reactor 26, being firstintroduced into a material lock chamber 27 through opened exterior lockgate 28. After closing of the lock gate 28, air contained in the lockchamber is sucked off. Thereafter an inner lock gate 29 can be openedand the solids can be introduced into the shaft reactor 26. In order tointroduce further solids, the inner lock gate 29 is closed again and thegas entered into the lock chamber 27 from the shaft is sucked off.Thereafter the outer lock gate 28 may be opened for a new batch ofsolids to be introduced.

The solids pass through the reactor shaft. in the form of a particulatesolids bed 30 as illustrated diagrammatically in FIG. 4. The particulatesolids bed is supported by a fire grate element 31 serving as adischarge element, provided in the lower region of the shaft reactor 26.The fire grate element has a prismatic configuration and is fitted as arocking grate being pivotal in the dry distillation reactor about ahorizontally extending axis 32. It is moved so as by rocking motion todischarge the solids residue still remaining from the bed of particulatesolids after dry distillation and combustion, i.e. ashes or cinders.

The dry distillation reactor 2 is composed of individual segments 33,34, 35 which enclose the shaft space and which for the formation of theshaft reactor 26 are stacked onto one another in a gas-tight manner. Forthat purpose the segments comprise connecting elements 36 which fit oneanother in their connecting planes, extending transversely, moreparticularly, essentially normal to the main direction of movement ofthe solids to be converted in the particulate solids bed, that ishorizontally in the working example. The connecting elements of allsegments are of uniform design. As for the remainder each segment,however, is designed in accordance with the technical objective it is tomeet. Thus, the segments 33 and 34 comprise flaps 38, 39 which arepivotal in the shaft reactor 26 about axes 37, which are operable bydrive means 40 (see FIG. 5) provided outside the shaft reactor. The axes37 in the working example are provided in the same manner as the axes 32extending horizontally. In large scale dry distillation reactors theflaps 38, 39 are driven by motors. The flaps serve for loosening up andfor supporting the movement of the particulate solids bed, if necessaryfor breaking up of solids bridges formed in the particulate solids bedwhich interfere with the conveyance of the solids in the particulatesolids bed or with the discharge of solids residues from the interior ofthe shaft reactor 26 in the region of the grate element 31. The flaps 39in the middle segment 34 essentially support the material movement inthe particulate solids bed; by means of the flaps 38 in the region ofthe grate element 31 it is possible, if desired or required, to alsodischarge still uncombusted bulky material residues of the materialsubjected to dry distillation.

The structure of the particulate solids bed is of great importance for auniform dry distillation of the solids. The gases heating up the solidsmust pass through all regions of the particulate solids bed in a uniformmanner such that the solids are converted, i.e. dry-distilled, ascompletely as possible and are combusted in the lower region of theshaft in order for only non-combustible solids residues to remain, whichcan be discharged from the dry distillation reactor withoutinterference, if desired or required, with the actuation and support ofthe flaps 38 and the grate element 31. The solids residues emergethrough the outlet gap 41 between the grate element 31 and flaps 38 intoa residue space 42 in the bottom 43 of the reactor and, in the workingexample drop into an ashes box 44 which in FIG. 4 is illustratedschematically and only in part.

In the working example the gasification medium, generally air, isintroduced into the particulate solids bed 30 in the shaft reactor 26 byway of and through its shaft internals which serve for the movement ofthe particulate solids bed in the shaft and for supporting the dischargeof the non dry-distilled and combusted solids residues in the shaft.Both the grate element 31 as well as the movable flaps 38 and 39 aredesigned hollow and comprise gas feed means 45 of identical design, eachextending parallel to their axes 32 and 37 respectively as well as intheir interior gas spaces 46 in the grate element 31 and gas spaces 47inside the flaps 38, 39 and discharge apertures 48 in the grate element31 or, as the case may be, discharge apertures 49 in the flaps 38, 39through which the gasification medium is introduced into the particulatesolids bed 30. By way of the discharge aperture 49 in the flaps 38, thegasification medium flows at the outlet gap 41 in the region of thelower edge of the grate element 31 from below into the particulatesolids bed 30, as indicated in FIG. 4 by flow arrows 50. Gasificationmedium is introduced centrally into the particulate solids bed 30 by thegrate element 31 by way of its discharge apertures 48 which in theworking example are shown in the upper region of the grate element 39and by way of the outlet apertures 49 in the flaps 39. By moving theflaps 39 the introduction of the gasification medium may also be locallyvaried depending on requirements.

When feeding the gasification medium by way of the grate element 31 andthe flaps 38 and 39 a cooling of the grate element and the flaps in thehot particulate solids region is attained simultaneously with thecentral feeding of the gasification medium into the particulate solidsbed.

The dry distillation volatiles flow out of the shaft reactor 26 in theupper region thereof by way of the dry distillation gas duct 4 thereconnected into the gasification reactor 5.

The combination possibilities afforded by and the mutualinterchangeability of the segments 33, 34, 35 in view of their uniformlydesigned connecting elements 36 in the connecting planes and aninterchangeable design in the axial direction in the dry distillationreactor provide for an optimal adaptability of the dry distillationreactor 2 to various required conditions for the conversion of thesolids to be dry-distilled. In particular, the height of the shaftreactor may be varied in a simple manner or a segment having a straightshaft wall, as provided in the working example by the segment 35, may beexchanged against a segment equipped with movable flaps for supportingthe movement of the particulate solids bed as is possible in the workingexample with the segment 34. In the working example according to FIG. 4gas ducts 51 are in addition provided in the region of the connectingelements 36, which, for example, may serve for feeding furthergasification media, in particular, air but also air enriched with oxygenor may in a different manner, not illustrated in the working example,serve for the withdrawal of generated dry distillation gases. Allconnecting elements are in this context so designed that, when stackingthe segments, gas-tight connections are attained.

In FIG. 6 a detail of the dry distillation reactor 2 according to FIG. 4along section line VI for one of the connecting elements 36 isillustrated on a scale enlarged by comparison with FIG. 4. In theworking example each segment is composed of chamotte blocks 52, 53, 54.Depending on the size and circumference of the reactor shaft a singlesegment may be formed from a single chamotte block providing arectangular shaft cavity or from a plurality of adjoiningly arrangedchamotte blocks together outlining the periphery of the shaft interior.In the working example each segment corresponding to the squarecross-section of the shaft reactor 26 encompassing the interior of theshaft reactor 26 to be charged with solids, see FIG. 5. Each segment issurrounded by wall portions 55, 56, 57 which shut off the drydistillation reactor 2 from the outside in a gas-tight manner. The wallsections conventionally consist of steel sheet As shown in FIG. 6, thechamotte blocks 52, 53, 54 are each fitted to the wall sections 55, 56,57 on equally configured brackets 58 at a horizontal distance 59 fromthe vertically extending wall portions so that between the chamotteblocks on the inside and the wall sections on the outside a gap 60remains for each segment. This gap permits a mutual tension-free thermalexpansion of chamotte blocks and wall sections in relation to oneanother having regard to their different coefficients of thermalexpansion and which expand differently at the operating temperature ofthe dry distillation reactor. Moreover, the gap 60 being an intermediategas space, provides thermal insulation.

The support brackets 58 of the segments, in the working example, formpart of the connecting elements 36. The chamotte blocks 52, 53, 54 ofthe segments are so fixed to the support brackets 58 that when stackingand mutually connecting the segments a vertical spacing and free space61 between the chamotte blocks and the adjoining segment remains. Inthis manner undesirable pressure onto the chamotte blocks is avoided.The chamotte blocks are placed onto the brackets 58 in a gas-tightmanner. Between the support brackets and the chamotte blocks afire-resistant seal 62 is in each case provided, for example, a chamottematerial having plastic properties.

In the working example the gas-tight sealing of the connecting elements36 when stacking the segments 33, 34, 35 is attained by gasket elements63 between the outer wall sections 55 and 56 and 56 and 57 respectively.For this purpose connecting flanges 64, 65 are provided on the wallsegments between which the sealing gaskets 63 are inserted. Theconnecting flanges 65 are fitted to the brackets 58, see FIG. 6. Thesealing of the segments in the connecting elements 36 by thefire-resistant sealing means 62 and by means of the sealing gaskets 63takes place in such a manner that not only the interior of the shaftreactor 26 is sealed against the outside, but that also all intermediatecavities 60 between the inner chamotte blocks and the exterior wallsections are sealed in relation to one another. In this manner theformation of vertical gas flows along the cool exterior walls of the drydistillation reactor from one segment to the other is avoided, whichcould impair the desired process performance in the dry distillationreactor substantially. In the working example the brackets 58 to whichthe connecting flanges 65 are fitted, are welded to the wall segments55, 56, 57 in a gas-tight manner. The intermediate cavities 60 are bythis design thus closed off in a gas-impervious manner in eachconnecting plane of a segment. As for the remainder, the intermediatecavities 60 are open, however, so that, if desired or required, gasentering these intermediate cavities between the wall sections and thechamotte blocks or optionally barrier-forming air additionallyintroduced by way of the gas ducts 51, can re-enter the interior of theshaft 26 by way of the free cavities 61, see flow arrows 66.

In the working example the bottom 43 of the reactor is likewise formedout of chamotte blocks. The chamotte blocks are so shaped and arrangedthat the residue space is provided with a downwardly constrictingcross-section so that solids residues leaving the shaft reactor 26 slideover downwardly sloping chamotte block walls into the ashes box 44. Thebottom 43 of the reactor comprises a connecting flange 67 for thestacking and connection of the lowermost segment 33 designed in the samemanner as any one of the connecting flanges 64 of the segments.

As regards the gasification reactor 5, which can either be used alone(FIGS. 2 and 3), or which is to be set up downstream of the drydistillation reactor 2 according to certain embodiments of the processof the invention (FIG. 1) a working example is illustrated schematicallyin FIG. 7 in longitudinal section. Details of the gasification reactorare shown in FIGS. 8, 9 as well as on a larger scale in FIGS. 10, 11.The cross-section of this gasification reactor is circular and thedesign is essentially axially symmetrical. The gasification reactorcomprises a large number of apparatus components, designed in a similarmanner as in the case of the dry distillation reactor 2, in particular,as regards the connecting elements in the connecting planes of thesegments for assembling the reactor shaft as well as the material feedand the ash withdrawal means. Thus, the material lock means 6 of thegasification reactor, which in the working example enters sideways intothe upper region of the gasification reactor, includes a material lockchamber 68 having two lock gates, an exterior gate 69 and an interiorgate 70 which are movable independently from one another and which closethe lock chamber in a gas-tight manner and thereby permit air havingentered the lock chambers 68 during the feeding of material when theexterior lock gate 69 is open or dry distillation gas having entered thelock chamber 68 whilst the inner lock gate 70 is open to be sucked off,all this in the same manner as for the solids feed means 1 of the drydistillation reactor.

Inside the cylindrical interior 71 of the gasification reactor 6 theintroduced material to be gasified once again forms a particulate solidsbed, which in the working example is supported by a grate 73, acting asthe discharge element, rotatable about an axis 72. In the workingexample this axis 72 is also the axis of symmetry of the gasificationreactor. For rotation a drive shaft 74 is fitted to the rotary grate,which is conducted upwardly out of the gasification reactor and hence isdrivable by way of a gear drive means, not shown in the drawing, aboutthe axis 72 in the direction of rotation 75. The movement may take placecontinuously or stepwise. The rotary grate 73 is provided in thegasification reactor underneath a constriction 76 formed in the interior71 which radially constricts the particulate solids bed in the shaftreactor. Such constrictions effect a rearrangement of the particulatesolids material and avoid bridge formations and undesirable channellingin the particulate solids bed, which would result in inhomogeneousgasflows in the particulate solids bed and in uneven conversion of thematerial to be gasified, so that possibly locally limited regions of theparticulate solids bed may burn through without contributing anything tothe gas generation.

As in the case of the dry distillation reactor, for assembling thegasification reactor stackable segments 78, 79 adapted to be stackedonto a segment base 77 by way of connection planes, which once again areessentially normal to the main direction of movement of the solids inthe particulate solids bed, i.e. extending horizontally, are providedwith connecting elements 80 of the same nature. Accordingly, thesegments of the gasification reactor as well are mutuallyinterchangeable so that the gasification procedures in the gasificationreactor can be optimised and adapted to the required conditions forgenerating a high-quality fuel gas, that the desired cracking of highmolecular weight hydrocarbon components in the dry distillation gastakes place as well as a gasification as complete as possible isattainable of the materials introduced in the form of a particulatesolids bed. In the working example the segment 79, for example, forconstricting the particulate solids bed in the interior 71 and for theformation of a constriction 76 comprises an inwardly directed region 81,where the material is thicker. This segment, in the event that theconstriction 76 should for specific application conditions be providedin a different position, for example, farther down in the interior 71,can be interchanged with a segment having straight interior walls, forexample, against a segment 78, or there may, in addition, be provided afurther segment for forming a second constriction. Accordingly, theinterchangeability of the segments based on their equally designedconnecting elements 80 results in a high variability in the technicaldesign of the gasification reactor 5.

In the case of the gasification reactor 5 as well the segments 78, 79 inthe working example comprise tubular chamotte blocks 82, 83, each beingplaced, radially spaced, for the formation of an intermediate cavity 84between an outer annular wall segment 85, 86 and chamotte blocks 82, 83on support brackets 87 in a gas-tight manner by means of refractorysealing means 88 so that the intermediate cavities 84 are sealed off ina gas-tight manner. Differences in thermal expansion between thechamotte blocks and metallic wall sections are accommodated by theirbeing spaced apart by way of the intermediate cavities, the intermediatecavities 84 in addition provide thermal insulation. The connectingelements 80 are designed analogously to the connecting elements 36 ofthe dry distillation reactor 2. For gas-tight sealing between thestacked segments the connecting elements 80 once again compriseconnecting flanges 89 with gaskets 90 provided between the flanges.

In the working example the segment base 77 is designed, with regard toits wall structure, in the same manner as a segment 78 or 79. Itcomprises chamotte blocks 91, encompassing the interior 71 in the lowerregion of the gasification reactor 5 and being arranged in spaced apartrelationship from the outer wall segments 92 so that in the segment baseas well an annular cavity 93 is brought about between outer wallsections 92 and chamotte blocks 91. The wall sections 92 are fitted tothe bottom 94 of the gasification reactor. In the working example thespacing between the chamotte blocks of the segment 77 and its wallsections 92 corresponds to the spacing between the chamotte blocks 82,83 and the wall sections 85, 86 of the segments 78, 79. On the segmentbase 77, for the gas-tight connection of the first segment to be stackedonto the segment base, i.e. of segment 78 in the working example, aconnecting flange 95, identical to the connecting flange 89 of aconnecting element, is fitted to the upper base edge.

Likewise, on the reactor head 96 of the gasification reactor 5 aconnecting flange 97 corresponding to the connecting flanges 89 of theconnecting elements is provided, serving for the connection of whateveris the last one of the stacked segments, i.e. segment 79 in the workingexample. Accordingly, any one of the segments of the gasificationreactor may be connected to the segment base 77 and reactor head 96 inthe same manner as to any one of the remaining segments.

In order to improve the gas tightness of the intermediate cavities 84 inrelation to the reactor interior (e.g. in the event of cracks forming inthe chamotte), it is preferred for the outer periphery of the chamottelining to be provided with a gastight covering of any suitable material,e.g. of sheet metal. To compensate for thermal expansion differences agap may be provided as well between such covering and the chamotteblock, provided that access of air or other gaseous medium to such gapis blocked off in any suitable manner, e.g. by resilient seals resistantto the temperatures there prevailing being provided at the top andbottom of the gap between the chamotte block and the cover or in anyother manner.

Instead of chamotte it is possible to employ any alternative suitablyrefractory material.

What is taught in the preceding two paragraphs in connection withreactor 2 applies equally to reactor 1.

The wall thickness of the chamotte blocks or other refractory blocks isselected according to two criteria: the desired heat insulation effectand the desired heat storage capacity. The greater the thickness thegreater will be the heat storage capacity. A high heat storage capacityprolongs the time required for heating up the apparatus. On the otherhand, a high heat capacity enhances temperature stability under variablethroughput rates. It also permits operating the reactor temporarilyunder very low load or even zero load conditions and resumption ofnormal load operating conditions without serious drop in temperature.

In the region of the rotary grate 73 an embers bed 98 encompassing theparticulate solids bed around the rotary grate 73 in an annular fashionis generated in the interior 71 of the gasification reactor by theintroduction of gasification media into the particulate solids bed. Thegasification medium in the working example essentially enters theparticulate solids bed through the rotary grate 73. For this purpose therotary grate as well as its drive shaft 74 are of hollow design andcomprise gas passages 99, 100 and gas chambers 101, 102 as well asapertures 103 at the gas chamber 102 for gas discharge therefrom. Thegas feed passage 99 passes through the hollow interior of the driveshaft 74, the gas passage 100 interconnects the gas chambers 101, 102 ofthe rotary grate 73. The gas flow in the gas passages and gas chambersis indicated by flow arrows 104. In the gas passage 99 the gasificationmedium is introduced by way of the gasification medium feed duct 7 whichis not shown in FIG. 7. The gasification medium first flows from the gaspassage 99 through the gas chamber 101 in order to there cool the rotarygrate 73 in the region of the embers bed 98 in the particulate solidsbed. The apertures 103 for the discharge of the gasification medium fromthe gas chamber 102 are provided above the embers bed 98. Thetemperature in the embers bed is controlled by way of the gasificationmedium feed. In the working example a temperature of about 1000° C. isset up in the embers bed, at which temperature even high molecularweight hydrocarbon components in the dry distillation volatiles arecracked.

Gasification media are also admitted to the gasification reactor 5 inthe region of the connecting elements 80 along the connecting planes ofthe segments. In analogy to the connecting areas of the segments of thedry distillation reactor pipe ducts 105 also enter the gasificationreactor in the intermediate cavities 84, 93 between the chamotte blocks82, 83, 91 and external wall segments 85, 86, 92. The pipe ducts 105 areconnected to the gasification media duct 7 by manifold ducts 106. Themanifold ducts 106 are illustrated only schematically in FIG. 7. Thegasification media enter into the interior 71 of the gasificationreactor 5 through cavities 107 (the flow of the gasification medium isonce again indicated by flow arrows 108). The cavities 107 are in eachcase provided at the connecting localities between the segments 78, 79on the one hand, and the connecting localities of the segments on thesegment base 77 and to the reactor head 96 between the chamotte blocks82, 83, 91 and the support brackets 87 of the respective adjoiningsegment 78, 79, respectively the segment base 77 or the reactor head 96.The overall amount of gasification media is introduced in relation tothe gasifiable solids content of the material to be gasified in theparticulate solids bed in a substoichiometric ratio in order to producehigh-quality fuel gas. The dry distillation volatiles to be convertedflow into the gasification reactor 5 by way of the dry distillation duct4 which in the working example enters into the reactor head 96.

The rotary grate 73 acting as a discharge element in the working examplecomprises two grate elements 109, 110 which, as part of the rotarygrate, viewed in the direction of main movement of the solids, aremutually vertically spaced apart and succeed each other in theparticulate solids bed at different levels. The grate elements 109, 110thus influence the material conveyance in the particulate solids bed attwo action levels. The exterior configuration of the grate elements isapparent from FIGS. 8, 9 representing transverse sections along sectionlines VIII—VIII and IX—IX according to FIG. 7. In the working examplethe grate elements 109, 110 are of pyramidal configuration. Theirconfigurations differ one from the other: the grate element 110 has theshape of a pyramid of square plan view, FIG. 8, the grate element 109forms a pyramid which is hexagonal in plan view, FIG. 9. In both grateelements 109, 110 the pyramid apexes are upwardly directed in thereactor shaft interior, where they merge into tubular collars 111, 112,on the one hand serving for the interconnection of the grate elements toone another and in the other case for connection to the drive shaft 74,see FIG. 10. Thus, the collar 111 of the grate element 109 is fixed tothe bottom 113 of the grate element 110, thereby being arranged radiallyspaced in relation to the drive shaft 74, whereby between the collar 111and the exterior surface of the shaft a gap is formed for providing thegas passage 100 interconnecting the gas chambers 101, 102. The collar112 of the grate element 110 is welded to the drive shaft 74.

When turning the drive shaft 74 the solids particles in the particulatesolids bed are moved by the grate elements 109, 110 whereby, inparticular, material bridges or channelling in the particulate solidsbed, which promotes flame breakthrough in local regions of theparticulate solids bed, are broken up. In particular, the grate element110, provided above the embers bed 98, thus acts as a means for blockingflame breakthrough in the particulate solids bed.

The pyramidal configuration of the grate elements replaces in anadvantageous manner grate elements having stirrer arms or worm volutionsmoved inside the particulate solids bed as are known, for example, fromDE 197 55 700 A1. As compared with these known means for providingmovement of the particulate solids bed the pyramidal grate elementsaccording to the invention provide the additional advantage that theyform hollow bodies and are cooled by the gasification media which areintroduced through the hollow bodies into the particulate solids bed.Cooling of the grate elements is necessary particularly where in theregion of the grate elements a high temperature embers bed is created.

Below the rotary grate 73 the fuel gas duct 9 for the withdrawal of thegenerated fuel gas is connected and also the discharge region fordischarging the solids residues from the gasification reactor 5 isformed. For the ashes discharge, which in FIG. 1 is denoteddiagrammatically by the reference symbol 10, a central aperture 115 isprovided in the funnel-shaped shaft bottom 114. The ash slides in theintermediate cavity 116 (see FIG. 10) between the rotary grate bottom 17and the shaft bottom surface which slopes downwardly in funnel-likemanner into the central aperture 115. It is advantageous to so tune thewithdrawal rate of the ash that, if possible, no non-converted carbonresidues of the gasifiable material feed are retained in the dischargedash. FIGS. 10, 11 show a special design of the bottom 117 of the rotarygrate for that purpose.

In FIGS. 10, 11 the rotary grate bottom 117 above the funnel-shapedshaft bottom 114 is illustrated on a larger scale as a detail of thegasification reactor 5 according to FIG. 7. To the underside of therotary grate bottom 117 a baffle formation is fitted, which in theworking example is composed of an annular external and an annularinternal solids guide means 118, 119, which cause the ash sliding overthe shaft bottom to be dammed up, permitting only finely particulate ashmaterial to exit in the arrow direction 120 into the central aperture115 and at the same time controlling the rate of discharge of the ash.In this context the maximum particle size of the ash is determined by agap 121 left between the last solids guide means 119 viewed in thedirection of conveyance of the ash and the sliding surface for the ashon the funnel-shaped shaft bottom 114. In order that the discharge offinely particulate solids residues cannot be blocked by coarser slag,forwarding formations 122 are provided on the rotary grate bottom 117 inthe region of the baffle device, which turn over the ash layer in theinterspace 116 in the rotary direction 75 when the rotary grate 73 turnsabout its axis 72 and, if necessary, causes slag lumps to be comminuted.In the working example the forwarding formations 122 are providedbetween the two solids guide formations 118, 119. The forwardingformations are radially directed in relation to the axis 72 (see FIG.11) and support the ash discharge through the gap 121. Depending on theparticular application, the forwarding formations may also be ofscoop-like design, thereby to lift and rearrange part of the ash duringmovement of the rotary grate. In the working example the outermostsolids guide means 118 and the forwarding formations 122 are welded tothe rotary grate bottom 117. The innermost solids guide means 119 is sofixed to the forwarding formations 122 at a vertical distance from therotary grate bottom that below the rotary grate bottom 117 a flowpassage 123 in the form of an annular gap or series of apertures isretained. Primarily the fuel gas is discharged through the annular gapafter having flown through the embers bed 98 and the ash dammed up inthe interspace 116, towards the fuel gas duct 9. The fuel gas flow inthe interspace 116 through the flow passage 123 is schematicallydesignated by flow arrows 130, designating a meandering flow path.

In determining the size of the flow passage 123 and the gap 121 for ashdischarge, the object is to achieve a separation of the solids residuesfrom the fuel gas. The fuel gas is deflected in the interspace 116towards the flow passage 123. This is attained in that the lower edge ofthe outermost solids guide formation 118 in the intermediate space 116is lower than the upper edge of the innermost solids guide formation119, which limits the through-flow passage 123. The dimensions andarrangement of the solids guide formations are so selected that thethrough-flow passage for the exiting fuel gas is kept open, moreparticularly, is kept free of solids residues which may become dammed upin the discharge region. The flow resistance for the fuel gas whenflowing through the solids bed in the intermediate space 116 should bekept as low as possible. The solids guide formations retain the materialand reduce the flow resistance for the fuel gas.

For a central alignment and local stabilisation of the rotary grate 73in the interior 71 of the gasification reactor 5, a guide 125 fixed tothe rotary grate extends from the bottom 117 of the rotary grate forholding the rotary grate in its axial position and to preventmalalignment thereof which might result in density variations within theparticulate solids bed, thereby causing pressure being applied to therotary grate. In the working example the guide 125 consists of steelsheets at right angles to one another which are welded to the rotarygrate bottom 117 (see in cross-section FIG. 11).

The rotary grate 73 is rendered level-adjustable parallel to the axis 72in a direction of displacement 126. This makes it possible fordischarging the ash to modify the width of the gap 121 between thebaffle formation, in the working example between the inner solids guideformation 119 and the funnel surface of the shaft bottom 114. The widthof the gap is adjustable to the maximum permissible particle size forthe exiting ash particles. Beyond this, the rotary grate 73 can bepulled upwardly sufficiently for purposes of cleaning the ash dischargeformations. The sliding incline of the funnel-shaped shaft bottom 114also plays a decisive role for the ashes discharge. Accordingly, thesegment base 77 illustrated in FIG. 10 may be suitably exchanged againsta segment base comprising a shaft bottom having a greater or lesserinclination.

A modification of the gasification reactor according to FIGS. 7, 8, 9,10, 11 is shown in FIGS. 12, 13, 14. In FIGS. 12, 13, 14 allconstruction elements of the gasification reactor having analogousfunctions as described above with reference to the working examples ofFIGS. 10 to 11 are denoted by the same reference numbers, however, withthe addition of the letter “a”.

In the gasification reactor 5 a according to FIG. 12 the generated fuelgas is withdrawn centrally upwardly from the shaft reactor. For thispurpose the drive shaft 74 a is connected to a drive element 127,provided in the overhead region of the gasification reactor above theparticulate solids bed, and turns the drive shaft 74 a and the rotarygrate 73, including the grate elements 109 a and 110 a in the directionof rotation 75 a. The drive shaft 74 a is of hollow design in the samemanner as in gasification reactor 5 according to FIG. 7 and functions asa gas withdrawal pipe 128 discharging at its upper open end into a fuelgas chamber 129, to which the fuel gas duct 9 a is connected.Accordingly, the generated fuel gas flows in the direction of the flowarrows 130 from the lower region of the gasification reactor, initiallythrough the intermediate space 116 a between the solids guide formations118 a, 119 a underneath the rotary grate bottom 117 a and thethrough-flow passages 123 a towards the fuel gas inlet 131 of the gaswithdrawal pipe 128 and hence in an upward direction to the fuel gaschamber 129 and to the connection to the fuel gas duct 9 a. The solidsresidues not gasified in the gasification reactor 5 a on the other handdrop through a central aperture 115 a in the chamotte block 91 a,serving to form the shaft reactor bottom 114 a, into an ash chamber 132in the same way as in the embodiment according to FIG. 7.

This way of conducting the generated fuel gas through the central gaswithdrawal pipe 128 in an upward direction out from the gasificationreactor offers the advantage that only very fine solids particles willbecome entrained in the fuel gas being withdrawn, which in the event ofvery high requirements as to freedom from dust of the fuel gas to bewithdrawn may be retained in additional filter means provided in thefuel gas duct 9 a. Of particular importance in relation to thewithdrawal of the fuel gases within the drive shaft 74 a is, however,particularly the possibility of heat exchange between the hot fuel gasbeing discharged from the gasification reactor and the cold gasificationmedium being introduced into the gasification reactor. For this purposethe drive shaft 74 a is surrounded by a gas pipe 133, the upper pipe end134 of which is welded in a gas-tight manner, in this working example,to the drive shaft 74 a below the drive element 127 and comprises inletapertures 136 for the gasification medium, which communicate with agasification medium chamber 135. The drive shaft 74 a and the gas pipe133 enter or pass through the gasification medium chamber 135 in agas-tight manner. The gasification medium feed line 7 a feeds into thegasification medium chamber 135. The gasification medium flows throughthe inlet apertures 136 in the gas pipe 133 in the direction of flow 137in the intermediate space 138 between the inside of the gas pipe 133 andthe outside of the drive shaft 74 a to the gas chambers 101 a and 102 a,which are interconnected by the gas passage 100 a. On entering theinterior 71 a of the gasification reactor 5 a, the gasification mediumwhich in the gasification medium chamber 135 will generally still be atroom temperature, takes up the heat of the hot fuel gas being dischargedfrom the gasification reactor through the gas withdrawal pipe 128 in thedrive shaft 74 a and being thereby warmed up, flows into the embers bed98 a in the lower region of the particulate solids bed in the interior71 a of the gasification reactor. In order to improve this heat transferthe wall of the pipe (drive shaft) 74 a may be equipped with heattransfer ribs or webs (not shown). In FIG. 12 the particulate solids bedis diagrammatically illustrated—in particular, by markings representingthe particulate solids bed surface in the shaft interior—and is denotedby reference number 139.

As for the remainder, the gasification reactor Sa according to FIG. 12is of analogous construction to the gasification reactor according toFIGS. 7, 8, 9. The material to be gasified is introduced into theinterior 71 a by way of a material lock chamber 68 a comprisingappropriate lock gates, an outer and an inner lock gate 69 a, 70 a. Thecylindrical interior 71 a is outlined by segments 78 a, 79 a includingconnecting elements 80 a, the segments, depending on their desiredeffect on the particulate solids bed being designed to homogenise theformer and are, if desired or required, mutually interchangeable. Thesegments include pipe ducts 105 a for feeding gasification medium. Thegasification media are introduced by way of the pipe ducts into theintermediate cavities 84 a in the outer wall region of the gasificationreactor 5 a, they then flow by way of the intermediate cavities 107 abetween the chamotte blocks 82 a, 83 a of the segments into thecylindrical interior 71 a filled with heaped particulate solids.

In the embodiment according to FIG. 12 the grate elements 109 a and 110a of the rotary grate 73 a are only slightly modified in relation to thegrate elements 109 and 110 according to FIGS. 7, 8, 9, in which contextthe grate element 110 a once again acts as a flame breakthrough blockingmeans in the particulate solids bed. The grate elements 109 a and 110 aare illustrated on a larger scale in FIGS. 13, 14. Although theycomprise the same pyramidal configuration as shown for the grateelements 109 and 110 in FIGS. 8, 9, the bottoms of the grate elements109 a and 110 a are, however, of different design. Thus, in the case ofthe grate element 110 a for the gas chamber 102 a a bottom element (seefor comparison bottom 113 in the embodiment according to FIG. 7) isomitted; the gasification medium accordingly flows freely from the gaschamber 102 a into the particulate solids bed 139 and into the embersbed 98 a which is formed in the heaped solids in that position. Therotary grate bottom 117 a of the grate element 109 a is closed as in thecase of the grate element 109, however, the drive shaft 74 a passesthrough the rotary grate bottom and its open end for the fuel gas inlet131 terminates below the rotary grate bottom 117 a . The rotary gratebottom slopes downwardly towards the central aperture 115 a in the shaftbottom 114 a in a pyramidal configuration.

The drive shaft 74 a according to the embodiment of FIG. 12 can likewisebe displaced in axial direction 140 (see FIG. 14) such that the width ofthe gap 121 a for the passage of ash into the ash chamber 132 can beadjusted to a predetermined particle size of the ash, depending onrequirements. Once again a guide formation 125 a is fixed to the rotarygrate bottom 117 a which stabilises the position of the rotary grate inthe particulate solids bed 139 inside the shaft reactor. The guideformation is once again made of steel sheet baffles at right angles toone another.

For conveying the added gasifiable material, a material distributor isfitted to the circumference of the gas pipe 132 in the inlet region ofthe shaft reactor, which, when the drive shaft 74 a rotates, moves aboutthe material by means of agitating baffles 141, extending into theparticulate solids bed.

Any one of the gas generators described with reference to FIGS. 7 to 14can also be used independently to perform the processes according to theinvention, i.e. without receiving dry distillation volatiles produced ina separate dry distillation reactor apparatus as described withreference to FIG. 4. In that case, the upper region represented bysections 78, 79 will accommodate the dry distillation zone. If theprocess is to be performed in accordance with FIG. 3, i.e. with the drydistillation zone being operated in co-current flow mode, it ispreferred to do so using a solids charge having a modest moisturecontent, preferably of not more than about 15% w/w and composed ofsolids having favourable bed forming characteristics and which carboniserelatively readily without producing excessive amounts of condensablevolatiles. In that case, the embers bed maintained near the solidsdischarge region in segment 77 alone and the features thereof relatingto the constrictive pathway through which the embers bed and the solidsresidues must pass together with the fuel gas stream are solelyresponsible for achieving high quality fuel gas characteristics. In thatcase, it may be particularly preferred to also increase the height ofthe commencement of the constrictive pathway between the outermostperiphery of the lowermost grate element 109 and the inner periphery ofthe cylindrical upright section of the chamotte block 101. This may bedone by providing a cylindrical or prismatic vertical wall portion ofappreciable height (see FIG. 10) between the inverted conical orpyramidal bottom portion of the grate element 109 and the conical orpyramidal upper portion of that grate element. The greater the height ofthat wall portion, the greater will be the increase in length of theconstrictive pathway and the greater will be the effect, provided thereis still sufficient exothermic reaction being maintained there in orderto maintain satisfactory cracking conditions. If necessary, additionaloxygen must be injected to react exothermally with any carbonaceousmatter still present in the bed.

The above lengthening of the constrictive pathway can be appliedregardless of whether the apparatus of FIGS. 7 to 14 is operated in themanner of FIG. 1, 2 or 3. The manner of FIG. 2 is preferred if theapparatus of FIGS. 7 to 14 is employed alone. In that event, it may bepreferable to increase the height of the dry distillation zone, e.g. byadding a further modular segments The dry distillation volatiles riseupwards through the bed in counter-current to the solids of the bed bysuction being applied to pipe 4 in the head section 96. The volatileswill thereafter be returned into the gasification zone, through one ofthe feed pipes 105 below the level where oxygen-containing gas isintroduced for maintaining partial combustion in the dry distillationzone.

It has been found that, performing the present invention, in particularthe gasification stage, in a shaft reactor of circular cross-section,which is ideally done, using rotary grate elements as herein disclosed,offers considerable advantages as compared with shaft reactors of squareor rectangular cross-section. Using the internals herein disclosed,material conveyance and bed uniformity are enhanced. Because of thehigher volume to wall area ratio, thermal efficiency is improved andless material is needed for the construction of the apparatus.

Particularly in those cases, where a significant degree of pyrolysis,i.e. dry distillation takes place in the upper region of this reactorvessel which accommodates the gasification zone, it is preferred toextend the height of the reactor vessel sufficiently in order toaccommodate and provide at least one further, i.e. rotary third grate ordischarge element coaxial with the aforesaid preferably two grateelements extending into the dry distillation region of that reactorvessel. The purpose of this further grate or discharge element is tocontrol the rate of travel and the evenness of the particulate solidsbed in the region where dry distillation takes place, before enteringthe gasification zone. This further grate element may likewise serve asa means for feeding oxygen-containing gas into the region where drydistillation takes place, preferably with feed control means separatefrom those controlling the supply of gasification medium to thegasification zone.

Referring now to FIGS. 15 to 18, integers equivalent in function tointegers shown in FIGS. 7 to 14 will be denoted by the same referencenumbers, except for the addition of the suffix “b”. They will not bedescribed again except in order to show differences from theircounterparts in the remaining figures. These differences are primarilythe following. The cylindrical portion 71 b of the reactor has beenupwardly extended substantially by a portion 271, thereby to extend theheight of the downwardly moving solids bed feeding the pyrolysis or drydistillation region of reactor 5 b. The capacity of the solids feedregion leading into this portion 271 has been also increased and at thesame time constructionally simplified and improved by a funnel-shapedhopper formation 272 supplied by the material lock means 68 b, 69 b, 70b which are automatically actuated in response to signals generated bybed level sensing means (not shown) inside the hopper formation 272. Asin previously described embodiments, rotary agitating and bed reformingmeans 141 b driven by the drive shaft 74 b serves to form an even bedentering the cylindrical reactor shaft 271.

Optionally (not shown) the portion 271 may be insulated thermally.

The drive shaft 74 b and the feed pipe 133 b for oxygen-containing gasare surrounded concentrically in their portion extending from near theclosed top 273 of the hopper portion down to near the bottom region ofcylindrical portion 271 by a further feed pipe 274, so as to leave a gap275 between feed pipe 133 b and feed pipe 274. Also near the top 273 ofthe hopper formation 272 a feed nipple 276 for oxygen-containing gas,e.g. air or oxygen-enriched air enters the hopper portion in the spaceabove the level 277 of the solids bed. Following the path of leastresistance, this oxygen-containing gas travels downwards, preferablythrough the gap 275 to the open bottom end of pipe 274, where it entersthe solids bed. This is facilitated further by a fire grate and rotarybed agitating member 278, which could be a further grate or dischargeelement similar to elements 110, 110 a, 110 b as described furtherabove. However, in the present modification this rotary agitating member278 is not of conical or pyramidal configuration but is composed by aplurality of short tubular members 279 fitted, more particularly weldedonto the outer periphery of the bottom end of pipe 274. In the presentembodiment four groups of three tubular members 279, each orientatedparallel to the axis 72 b of the drive shaft 74 b are welded to theouter periphery of pipe 274 so that a gap 280 is left between successivegroups of tubular members 279. The effect of these groups of tubularmembers is twofold. Firstly, rotation of the shaft produces an agitatingeffect and opens up a cavity in the bed near the bottom end of pipe 274into which oxygen-containing gas may flow. The tubular nature of thetubular members 279 moreover has the effect of providing passages forthe oxygen-containing gas into the region of the bed immediately abovethe member 278. The combined effect is to facilitate the partialcombustion in the dry distillation region of reactor 5 b.

A further difference of the embodiment of FIG. 15 resides in the designof the ash chamber 132 b and the means for separating the fuel gas,where it is being withdrawn from the ash and/or cinders entering the ashchamber 132 b. It will be seen that in FIG. 15 the fuel gas inlet 131 bof shaft 74 b extends some distance below the rotary grate bottom 117 b,well below at the ash outlet gap 121 b, leaving an annular gap 281 inthe central aperture 115 b between the solids guide formation 119 b anddrive shaft 74 b. The guide 125 b differs from guide 125 in earlierembodiments by the provision of a sleeve 282, surrounding the bottom endof shaft 74 b, and held in place by braces 283. The sleeve 283 isextended downwardly by an outwardly flaring conical baffle 284.

The ash chamber 132 b itself comprises an upper cylindrical portion 285terminating approximately at the level of the lower edge of the baffle284 and from there tapering conically at 286 toward a cylindrical ashcollecting box 287 having an ash withdrawal outlet 288 and an inlet 289for oxygen-containing gas, preferably having an oxygen content higherthan air, e.g. a technical grade oxygen of 80% or higher, depending onthe residual carbon content in the solids residue, the object being toproduce ash with a minimum of carbon.

Referring specifically to FIGS. 17 and 18, it will be seen that thepyramidal top 290 of the lowermost grate member 109 b is followed indownward direction by a prominent cylindrical peripheral wall portion291 (as is also the case in FIG. 15). In contrast to FIG. 15, the solidsguide member 118 b, here denoted as 292 is moved closer to the reactorwall 293 and forms a direct continuation of wall portion 291 of gratemember 109 b, extending downwardly from the bottom 117 b of the latter.Accordingly, there is formed a prominent constricted annular passage 294through which the embers bed 8 b must travel. This passage is followedby the inwardly downwardly sloping funnel-shaped continuation of theconstricted pathway defined between the funnel-shaped bottom 114 b ofthe reactor shaft, the bottom edge 295 of solids guide formation 292 andthe adjustable gap 121 b defined by the bottom edge of solids guideformation 119 b.

In the use of reactor 5 b the embers bed 98 b, including gas passingtherethrough in co-current, moves in downward direction towards thecentral aperture 115 b. In doing so, the embers bed passes through theannular constricted passage 294, down the slope of bottom 114 b andfinally through gap 121 b into central aperture 115 b. There the solidsresidues drop down onto the baffle 284 and the funnel-shaped wallportion 286 into the ash box 287. In the ash box, depending on theresidual carbon content, oxygen and/or air is admitted through an inletrepresented by a nozzle 289 in substoichiometrical amounts to convert bypartial post combustion the residual carbon into heat, carbon monoxideand CO₂ which is withdrawn together with the fuel gas product throughthe inverted funnel-shaped cavity formed by baffle 284 and through driveshaft 74 b.

The fuel gas, having passed in intimate contact through the embers bed,leaves the solids bed along its meandering pathway 130 b enteringthrough apertures 123 b also into the central aperture 115 b into thetop of ash chamber 132 b and from there—arrow 290—into the invertedfunnel-shaped cavity formed by baffle 284 and up into fuel gas inlet 131b of drive shaft 74 b. This gas pathway serves to cause disentrainmentof solids fines from the fuel gas.

Optionally, this disentrainment may be enhanced by internals inducing acyclonic spin to the gas to promote settlement of dust against theinside of baffle 284.

Finally, FIG. 15 shows gastight annular sheet metal screens 291separating the annular gas cavities 84 bbetween the refractory blocks 82b, 83 b, 91 b and the exterior reactor walls 92 b. The screens 291 areso dimensioned that an expansion gap 292 is left between the ceramicblocks and the screens. The screens are welded gastight onto the supportbrackets 87 b.

A particularly important use of the gas processor in a plant for theproduction of hydrogen is shown in FIG. 19. To begin with, the plantcomprises the above described dry distillation and gasificationreactors, in the working example a dry distillation reactor 142 and agasification reactor 143 as well as a gas motor 144, downstream of thegasification reactor, operated with the fuel gas produced in thegasification reactor. For heat recovery a heat exchanger 146, throughwhich flows motor exhaust gas, is provided in the motor exhaust passage145 of the gas motor 144; a heat carrier, for example, water, passesthrough the heat exchanger and takes up the thermal energy stillcontained in the motor exhaust gas. Feed and withdrawal ducts 147, 148for the heat carrier are indicated in FIG. 19 by corresponding flowarrows.

The gas motor 144 serves to drive a generator 149 for the generation ofelectrical energy. An electrolysis cell 150 is connected to thegenerator by means of which hydrogen and oxygen are producedelectrolytically. Both gases are conveyed to separate gas storage means,the produced hydrogen by way of a hydrogen duct 151 to a hydrogenstorage means 152, the oxygen by way of an oxygen duct 153 to an oxygenstorage means 154. Whereas the hydrogen and any excess energy generatedby the generator is available for withdrawal and general use, at leastpart of the produced oxygen is returned to the plant The oxygen ispumped by a feed pump 155 by way of a feed duct 153 a into a mixingchamber 156 and is there mixed with part of the motor exhaust gas andwith air and flows in the form of this gas mixture as gasificationmedium by way of a gasification medium line 157 to the gasificationreactor 143 and also by way of a gasification medium branch duct 158 tothe dry distillation reactor 142.

In the working example biomass in heterogeneous form, e.g. “yellow wastebag” or waste rubber, such as motor vehicle tyres or renewable rawmaterials such as straw or specially planted fast-growing energy crops,annual or perennial, are gasified in the dry distillation reactor 142.The heterogeneous biomass is fed into the dry distillation reactor 142by way of a feed duct 159 and is converted into dry distillationvolatiles by conversion with gasification media. The dry distillationvolatiles flow by way of a dry distillation gas duct 160 into thegasification reactor 143. In the gasification reactor the drydistillation volatiles are converted into fuel gas. For this purpose itis passed through a particulate solids bed, which in the working exampleis composed of biomass in a homogeneous form. For example shredded wood,charcoal or suitable wood pellets may be used as a homogeneous biomassand be introduced into the gasification reactor 143 by way of a materialfeed means 161. In the outlet region of the gasification reactor thebiomass—as already described with reference to the embodiment of FIG.7—forms an embers bed through which the dry distillation volatiles flow.In doing so, the high molecular hydrocarbon components and other tarcomponents in the dry distillation gas are cracked. The fuel gas beingdischarged from the gasification reactor is passed in a fuel gas line162 to the gas motor 144, if desired or required, after having beenpassed through a gas cleaning means 163 installed in the fuel gas line162. In order to clean the motor exhaust gases discharged by the gasmotor 144 and passed to the heat exchanger 146, a catalyst 164 may beemployed. In the working example the amount of exhaust gas passingthrough the catalyst 164 is regulated by means of valves 165, 166. Thevalve 166 is provided in a by-pass line 167 passing parallel to themotor exhaust gas duct 145.

The motor exhaust gas passed to the mixing chamber 156 is withdrawn byway of a gas duct 168 connected to the motor exhaust gas duct 145. Inthe working example the gas feed line 168 is connected to the motorexhaust gas duct 145, even before the exhaust gas enters the heatexchanger 146. Accordingly, the exhaust gas flowing into the mixingchamber 156 still has its exhaust gas temperature as determined by themotor. In order to set up the desired composition and concentration ofthe gasification medium, an air feed 169 is also connected to the mixingchamber 156.

A mixing chamber 170 for the gasification medium to be introduced islikewise provided upstream of the dry distillation reactor 142 beforethe gasification medium enters the reactor through a gasification mediumfeed line 171. In the working example the gasification medium branchline 158 connected to the mixing chamber 156 as well as an air feed duct172 enter into the mixing chamber 170.

In the plant illustrated in FIG. 19 there is thus recovered from biomassa valuable energy carrier, i.e. hydrogen, in an advantageous mannerbesides electrical energy and a recovery of thermal energy from motorwaste gases. The plant is self-sufficient in respect of the electricalenergy required for its operation and may accordingly be set uppreferably as an energy-generating plant at remote localities.

From the aforegoing it will be apparent that the invention is, on theone hand, based throughout on the single, uniform inventive concept ofconsistently generating a high quality fuel gas, substantially free ofcondensable high molecular weight contaminants by guiding the gasesbeing generated through the particulate solids bed(s) maintained in thegenerator as a well-configured high temperature embers bed so thatcomplete cracking of these contaminants can be attained far morecompletely by simpler means than according to the prior art. On theother hand, the invention includes numerous facets which interact bothcumulatively as well as symbiotically with the aforegoing to achievethis objective under the most varied circumstances as may arise both inhigh-tech as well as least developed circumstances. The invention offersthe potential of solving environmental problems under the most diverseconditions.

The flexibility of the inventive concept allows for numerousmodifications within the scope of the invention. Thus, the oxygengenerated in accordance with FIG. 19 can also be made available as aprimary by-product in remote areas, e.g. for medical as well astechnical purposes (e.g. welding). For use in the fuel gas generationprocess, the oxygen may also (at least in part) be used in substantiallypure form, for example, for injection into any one of the particulatesolids beds whenever a local increase in temperature is needed, eithercontinuously or temporarily and intermittently. If it is desired toenrich the oxygen content of oxygen-bearing gas, optionally even to theextent of using a technically pure grade of oxygen (e.g. 80% pure orhigher) in any part of the process, it is also feasible to employ othersources of such oxygen, not necessarily produced by air distillation,but optionally by alternative processes such as molecular sieve(zeolite) technologies, which may be more appropriate in a remotelocality.

In the installation according to FIG. 19 it may furthermore beadvantageous to provide for buffer storage facilities, such asgasometers and compressed gas tanks for the temporary storage of fuelgas and/or hydrogen produced to provide for fluctuating needs.

As regards the gasses produced in various stages of the processaccording to the invention, it is not essential that the entirety ofthese gases should be processed identically. It is, for example,possible for part of the dry distillation gases and/or gasificationgases to be withdrawn at a stage of the process where the purity is lessthan required for internal combustion engines in order for such somewhatlower grade fuel gas to be used in gas burners, e.g. for cooking andheating or for steam generation. A great need exists for cooking gas inremote rural underdeveloped areas to counteract the health hazards ofsmoke exposure in traditional cooking using open wood fires.

It is also possible to withdraw at least part of the dry distillationvolatiles at an early stage of the process for the actual recovery ofcondensable volatiles as useful products, e.g. for the recovery of woodtar and creosote for the impregnation of timber, for which a great needexists in rural underdeveloped areas, the recovery of methanol as a fueland the recovery of other by-products.

The process also permits the withdrawal, e.g. in a side stream of theprocess, of charcoal as an additional fuel product, useful as a“smokeless” fuel.

As an alternative to using the fuel gas directly as a fuel, it is alsopossible in manners known per se to perform the process so as tomaximise the yield of hydrogen (water gas reaction), in order to producehydrogen, e.g. for use in fuel cells.

Likewise, in a manner known per se it is possible to operate the processand apparatus according to the invention so as to produce a product gashaving the composition of synthesis gas if that is needed.

Finally, the process, as illustrated in FIG. 19 offers numerousadditional possibilities for recovering useful heat, e.g. in the form ofhot water for which a great need exists in sophisticated as well asleast developed communities. Besides the recovery of heat from theexhaust gases of gas fueled motors, heat may also be recovered fromcooling the engines as such. Any heat not needed for other purposes canbe used to preheat the gasification media in order to improve thethermal efficiency of the process as a whole. In order to achieve this,it is further possible to pass the gasification media in heat exchangewith the ashes of the dry distillation and gasification zones.

The claims which follow are to be considered an integral part of thepresent disclosure. Reference numbers (directed to the drawings) shownin the claims serve to facilitate the correlation of integers of theclaims with illustrated features of the preferred embodiment(s), but arenot intended to restrict in any way the language of the claims to whatis shown in the drawings, unless the contrary is clearly apparent fromthe context. The term “comprises” or “comprising” as used herein and inthe claims, has its customary non-restrictive meaning which required forits operation and may accordingly be set up preferably as anenergy-generating plant at remote localities.

From the aforegoing it will be apparent that the invention is, on theone hand, based throughout on the single, uniform inventive concept ofconsistently generating a high quality fuel gas, substantially free ofcondensable high molecular weight contaminants by guiding the gasesbeing generated through the particulate solids bed(s) maintained in thegenerator as a well-configured high temperature embers bed so thatcomplete cracking of these contaminants can be attained far morecompletely by simpler means than according to the prior art. On theother hand, the invention includes numerous facets which interact bothcumulatively as well as symbiotically with the aforegoing to achievethis objective under the most varied circumstances as may arise both inhigh-tech as well as least developed circumstances. The invention offersthe potential of solving environmental problems under the most diverseconditions.

The flexibility of the inventive concept allows for numerousmodifications within the scope of the invention. Thus, the oxygengenerated in accordance with FIG. 19 can also be made available as aprimary by-product in remote areas, e.g. for medical as well astechnical purposes (e.g. welding). For use in the fuel gas generationprocess, the oxygen may also (at least in part) be used in substantiallypure form, for example, for injection into any one of the particulatesolids beds whenever a local increase in temperature is needed, eithercontinuously or temporarily and intermittently. If it is desired toenrich the oxygen content of oxygen-bearing gas, optionally even to theextent of using a technically pure grade of oxygen (e.g. 80% pure orhigher) in any part of the process, it is also feasible to employ othersources of such oxygen, not necessarily produced by air distillation,but optionally by alternative processes such as molecular sieve(zeolite) technologies, which may be more appropriate in a remotelocality.

In the installation according to FIG. 19 it may furthermore beadvantageous to provide for buffer storage facilities, such asgasometers and compressed gas tanks for the temporary storage of fuelgas and/or hydrogen produced to provide for fluctuating needs.

As regards the gasses produced in various stages of the processaccording to the invention, it is not essential that the entirety ofthese gases should be processed identically. It is, for example,possible for part of the dry distillation gases and/or gasificationgases to be withdrawn at a stage of the process where the purity is lessthan required for internal combustion engines in order for such somewhatlower grade fuel gas to be used in gas burners, e.g. for cooking andheating or for steam generation. A great need exists for cooking gas inremote rural underdeveloped areas to counteract the health hazards ofsmoke exposure in traditional cooking using open wood fires.

It is also possible to withdraw at least part of the dry distillationvolatiles at an early stage of the process for the actual recovery ofcondensable volatiles as useful products, e.g. for the recovery of woodtar and creosote for the impregnation of timber, for which a great needexists in rural underdeveloped areas, the recovery of methanol as a fueland the recovery of other by-products.

The process also permits the withdrawal, e.g. in a side stream of theprocess, of charcoal as an additional final product, useful as a“smokeless” fuel.

As an alternative to using the fuel gas directly as a fuel, it is alsopossible in manners known per se to perform the process so as tomaximise the yield of hydrogen (water gas reaction), in order to producehydrogen, e.g. for use in fuel cells.

Likewise, in a manner known per se it is possible to operate the processand apparatus according to the invention so as to produce a product gashaving the composition of synthesis gas if that is needed.

Finally, the process. as illustrated in FIG. 19 offers numerousadditional possibilities for recovering useful heat, e.g. in the form ofhot water for which a great need exists in sophisticated as well asleast developed communities. Besides the recovery of beat from theexhaust gases of gas fueled motors, heat may also be recovered fromcooling the engines as such. Any heat not needed for other purposes canbe used to preheat the gasification media in order to improve thethermal efficiency of the process as a whole. In order to achieve this,it is further possible to pass the gasification media in heat exchangewith the ashes of the dry distillation and gasification zones.

The claims which follow are to be considered an integral part of thepresent disclosure reference numbers (directed to the drawings) shown inthe claims serve to facilitate the correlation of integers of the claimswith illustrated features of the preferred embodiment(s), but are notintended to restrict in any way the language of the claims to what isshown in the drawings, unless the contrary is clearly apparent from thecontext the term “comprises” or “comprising” as used herein and in theclaims, has its customary non-restrictive meaning which denotes that inaddition to any items to which the term relates, there may be includedadditional items not specifically mentioned.

1. A process for the generation of a fuel gas by dry distillation ofcarbonaceous solids in a dry distillation zone into which thecarbonaceous solids are fed via a solids supply and in which the solidsare heated, where applicable dried and are dry-distilled with theliberation of dry distillation volatiles and, by further conversion ofthose volatiles in a gasification zone in the presence of carbonaceoussolids passing through the gasification zone at least in part undergravity in the form of a bed of particulate solids, to whichgasification media are fed in substoichiometric quantities, the drydistillation volatiles withdrawn from the dry distillation zone enteringthe gasification zone and flowing through the bed of particulate solidsbeing there maintained in co-current with the direction of travel of thelatter, an embers bed being formed by the bed of particulate solids inthe terminal portion of the gasification zone in the region of a firegrate element acting further as a solids discharge element for theresidual solids after completion of the gasification, through whichembers bed the gas formed in the bed of particulate solids passes,whereby condensable volatiles components contained in the gas arecracked, and wherein the fuel gas so generated is withdrawn from thelower region of the bed of particulate solids of the gasification zone,wherein gas containing oxygen is introduced into the dry distillationzone in substoichiometric amount for generating heat by partialcombustion of the solids to be dry-distilled passing through the drydistillation zone in the form of a bed of particulate solids under theaction of gravity before the generated fuel gas product is separatedfrom ashes and any cinders and is withdrawn and forwarded for furtheruse, said process further comprising additional measures for furtherdecreasing the content of condensable dry distillation volatiles in thefuel gas product by increasing the intimate contact of the gases andvapours with the solids beds through which they pass, selected fromeither or both of the following: A) that the embers bed of thegasification zone is conducted from the higher lying regions of saidzone under gravity towards and through a constricted lower peripheralpassage region of the gasification zone defined between the outerperiphery of the fire grate element and the inner periphery of exteriorwalls of a reactor in which the process is performed, and in co-currenttherewith the dry distillation volatiles and gasification gases and anygaseous cracking products are passed in intimate contact with andthrough the embers bed and from there travels down a funnel-shapedinwardly sloping constricting pathway below the fire grate elementleading into and ending with the ash withdrawal region, where theseparation occurs between the ashes and any cinders and the generatedfuel gas product; B) that in at least one dry distillation zone in theform of a bed of particulate solids under the action of gravity the gaspresent in that zone passes through the solids in counter-current to thedirection of travel of the solids to be dry distilled, the solidsthereby being dry distilled and the dry distillation volatiles therebyformed in the dry distillation zone being withdrawn from the drydistillation zone near the solids supply region and that at least partof the dry distillation volatiles formed in the dry distillation zonewithdrawn from near the solids supply region feeding the drydistillation zone with carbonaceous solids are from there forwarded intothe gasification zone, where they, together with gasification gases andany gaseous cracking products, pass in co-current with and in intimatecontact with and through the embers bed of the gasification zone and aresubjected to cracking of condensable volatiles, before being separatedfrom ashes and any cinders and being withdrawn as a fuel gas product,subject further to the condition that, at least when feature A) isabsent and where the at least one dry distillation zone, wherein the bedof particulate solids and the gas present therein pass incounter-current to one another, is maintained in a first vessel,distinct and separate from a second vessel, wherein the bed ofcarbonaceous solids and the gases and vapours pass in co-current withone another, (i) the bed of particulate solids in the first vessel isthere combusted and gasified substantially entirely to solids residuesconsisting of ashes, cinders, any non-combustible solids components oruncombusted bulky material residues; and (ii) the solids residues of (i)are withdrawn from the first vessel for disposal; and (iii) the bed ofparticulate solids in the second vessel is formed from a solids supplyseparate from the first vessel.
 2. Process as claimed in claim 1,including the integers of A), wherein the fuel gas is withdrawn from theash withdrawal region along a meandering continuation of the aforesaidconstricting pathway.
 3. Process as claimed in claim 1, including theintegers of A), wherein the fuel gas is withdrawn in counter-currentheat exchange with gasification medium being fed to the gasificationzone.
 4. Process as claimed in claim 1, including the integers of A) andwherein at least part of the dry distillation volatiles formed in thedry distillation zone pass in counter-current to the bed of particulatesolids of the dry distillation zone through that bed and are withdrawnfrom near the solids supply region, feeding the dry distillation zonewith carbonaceous solids, and are from there forwarded, at least inpart, into the gasification zone; wherein the dry distillation takesplace, at least in part, in a first vessel separate from a secondvessel, in which the gasification zone is maintained; and wherein fromthe first vessel, solids residues composed predominantly ofnon-combustible solids residues are withdrawn from that region of thefirst distillation vessel which is remote from its solids supply region,whereas the second vessel is supplied with solids for forming its bed ofparticulate solids, at least in part not being the solids withdrawn fromthe said region remote from the solids supply region of the firstvessel.
 5. Gas generator suitable for performing the process as claimedin claim 1 for generating a fuel gas product, including solids feedermeans discharging into a solids supply portion of a dry distillationzone, in which dry distillation zone solids introduced by the solidsfeeder means are heated, dried if necessary and subjected to drydistillation, thereby to release dry distillation volatiles into agasification zone supplied with and containing a bed of gasifiablecarbonaceous solids downstream of the dry distillation zone andsupported on a fire grate device, restricting the rate of downwardmovement of the solids of the bed under gravity in co-current with drydistillation volatiles released from the dry distillation zone as wellas the gasification media and the generated fuel gas in the gasificationzone flowing through the particulate solids bed, a supply ofoxygen-bearing gases in the dry distillation zone supporting partialcombustion therein for heating the dry distillation zone and a supply ofgasification medium being provided for maintaining gasificationconditions in the gasification zone by the provision of feed lines forgasification media to be introduced into the particulate solids bedwhich enter into the gasification zone, at least the lower region of thebed of gasifiable carbonaceous solids being maintained in an embers bedcondition through which the dry distillation volatiles and volatilisedproducts of gasification pass in order to be subjected to thermalcracking and including an ash withdrawal region including a gasseparation zone and discharge passage for the generated fuel gas productand further including additional features adapted for further decreasingthe content of condensable dry distillation volatiles in the fuel gasproduct by increasing the intimate contact of the gases and vapours withthe solids beds through which they pass, selected from either or both ofthe following: a) that in relation to higher lying regions of thegasification zone (5; 5 a; 5 b) the fire grate device (73; 73 a), actingfurther as a discharge element for the solids residues of thegasification, defines a constricted peripheral passage (116; 116 a) forthe embers bed of the gasification zone between the outer periphery ofthe fire grate device (73; 73 a) and the inner periphery of the exteriorwalls (82, 85) of the gasification zone, which constricted peripheralpassage merges into a downwardly and inwardly funnel-like slopingconstricting pathway (116; 116 a) below the fire grate device leadinginto and ending with the ash withdrawal region (121; 121 a), where theseparation occurs between the ashes and any cinders and the generatedfuel gas product; b) that through at least one dry distillation zonesolids to be dry-distilled pass in the form of a particulate solids bed(30) under the action of gravity, wherein further a gasification mediumfeed means (3) for an oxygen-containing gas enters below the particulatesolids bed (2) and wherein for the withdrawal from the dry distillationzone of the dry distillation volatiles, formed with heat generation bypartial combustion of the solids in the dry distillation reactor, a drydistillation gas duct (4) is connected in the region of the solidssupply means (1) and so enters into a gasification zone, that the drydistillation gas flows through the particulate solids bed (139) in thegasification zone in intimate contact with and in co-current to thesolids material, subject further to the condition that, at least whenfeature a) is absent and where the at least one dry distillation zone,which is designed for the particulate solids bed therein and the flow ofdry distillation volatiles to pass in counter-current to one another, isto be maintained in a first vessel distinct and separate from a secondvessel, wherein the bed of carbonaceous solids and gases pass inco-current with one another, (i) the first vessel (2) is designed forthe bed of particulate solids to be combusted and gasified substantiallyentirely to solids residues consisting of ashes, cinders and anynoncombustible solids components or uncombusted bulky material residues;and (ii) has a discharge locality (22) at its bottom end for thedisposal of the solid residues; and that (iii) the second vessel (5) hasits own supply means (6; 68-70) for the introduction, separate from thefirst vessel (2), of gasifiable material which is to form the bed ofparticulate solids in the second vessel (5).
 6. Gas generator as claimedin claim 5, and including the integers of a), wherein the fuel gasdischarge passage(s) passes, at least in part, in heat exchangingcounter-current with a feed passage (133) for gasification medium and/oroxygen-bearing gas.
 7. Gas generator as claimed in claim 5, andincluding the integers of a), wherein the bottom (114; 114 a) of thedownwardly and inwardly sloping pathway has a funnel-shapedconfiguration, forming a sliding surface for the ash, feeding into acentral aperture (115; 115 a; 115 b).
 8. Gas generator as claimed inclaim 5, wherein at least part of the dry distillation zone (2) isaccommodated in a first reactor vessel (26) separate from a secondreactor vessel (71) accommodating the gasification zone (5), and a ductor passage (4) is provided for feeding dry distillation volatiles fromthe first vessel into the second vessel.
 9. Gas generator as claimed inclaim 5 and including the integers of b), wherein the solids to bedry-distilled pass through a dry distillation reactor (2) in aparticulate solids bed (30) under the action of gravity, wherein furthera gasification medium feed means (3) for an oxygen-containing gas entersbelow the particulate solids bed and wherein for the withdrawal from thedry distillation zone of the dry distillation volatiles, formed withheat generation by partial combustion of the solids in the drydistillation reactor, a dry distillation gas duct (4) is connected inthe region of the solids supply means (1) and so enters into agasification reactor (5) that the dry distillation volatiles flowthrough the particulate solids bed (139) in the gasification reactor (5)in co-current to the solids material.
 10. A process for the generationof a fuel gas by dry distillation of carbonaceous solids in a drydistillation zone into which the carbonaceous solids are fed via asolids supply and in which the solids are heated, where applicable driedand are dry-distilled with the liberation of dry distillation volatilesand, by further conversion of those volatiles in a gasification zone inthe presence of carbonaceous solids passing through the gasificationzone at least in part under gravity in the form of a bed of particulatesolids, to which gasification media are fed in substoichiometricquantities, the dry distillation volatiles withdrawn from the drydistillation zone entering the gasification zone and flowing through thebed of particulate solids being there maintained in co-current with thedirection of travel of the latter, an embers bed being formed by the bedof particulate solids in the terminal portion of the gasification zonein the region of a fire grate element acting further as a solidsdischarge element for the residual solids after completion of thegasification, through which embers bed the gas formed in the bed ofparticulate solids passes, whereby condensable volatiles componentscontained in the gas are cracked, and wherein the fuel gas so generatedis withdrawn from the lower region of the bed of particulate solids ofthe gasification zone, wherein gas containing oxygen is introduced intothe dry distillation zone in substoichiometric amount for generatingheat by partial combustion of the solids to be dry-distilled passingthrough the dry distillation zone in the form of a bed of particulatesolids under the action of gravity before the generated fuel gas productis separated from ashes and any cinders and is withdrawn and forwardedfor further use, said process further comprising additional measures forfurther decreasing the content of condensable dry distillation volatilesin the fuel gas product by increasing the intimate contact of the gasesand vapours with the solids beds through which they pass, selected fromeither or both of the following: A) that the embers bed of thegasification zone is conducted from the higher lying regions of saidzone under gravity towards and through a constricted lower peripheralpassage region of the gasification zone defined between the outerperiphery of the fire grate element and the inner periphery of exteriorwalls of a reactor in which the process is performed, and in co-currenttherewith the dry distillation volatiles and gasification gases and anygaseous cracking products are passed in intimate contact with andthrough the embers bed and from there travels down a funnel-shapedinwardly sloping constricting pathway below the fire grate elementleading into and ending with the ash withdrawal region, where theseparation occurs between the ashes and any cinders and the generatedfuel gas product; B) that in at least one dry distillation zone in theform of a bed of particulate solids under the action of gravity the gaspresent in that zone passes through the solids in counter-current to thedirection of travel of the solids to be dry distilled, the solidsthereby being dry distilled and the dry distillation volatiles therebyformed in the dry distillation zone being withdrawn from the drydistillation zone near the solids supply region and that at least partof the dry distillation volatiles formed in the dry distillation zonewithdrawn from near the solids supply region feeding the drydistillation zone with carbonaceous solids are from there forwarded intothe gasification zone, where they, together with gasification gases andany gaseous cracking products, pass in co-current with and in intimatecontact with and through the embers bed of the gasification zone and aresubjected to cracking of condensable volatiles, before being separatedfrom ashes and any cinders and being withdrawn as a fuel gas product,subject further to the condition that, at least when feature A) isabsent and where the at least one dry distillation zone, wherein the bedof particulate solids and the gas present therein pass incounter-current to one another, is maintained in a first vessel,distinct and separate from a second vessel, wherein the bed ofcarbonaceous solids and the gases and vapours pass in co-current withone another, (i) the bed of particulate solids in the first vessel isthere combusted and gasified substantially entirely to solids residuesconsisting of ashes, cinders, any non-combustible solids components oruncombusted bulky material residues; and (ii) the solids residues of (i)are withdrawn from the first vessel for disposal; and (iii) the bed ofparticulate solids in the second vessel is formed from a solids supplyseparate from the first vessel, said process including at least theintegers of B) and wherein, at least in the event that the drydistillation zone and the gasification zone are maintained in separatedry distillation and gasification vessels, solids residues composedpredominantly of non-combustible solids residues are withdrawn from thatregion of the dry distillation vessel which is remote from its solidssupply region, whereas the gasification vessel is supplied with solidsfor forming its bed of particulate solids at least in part differentfrom the solids residues withdrawn from the said region remote from thesolids supply region of the dry distillation vessel.
 11. Gas generatorfor generating a fuel gas product, including solids feeder meansdischarging into a solids supply portion of a dry distillation zone, inwhich dry distillation zone solids introduced by the solids feeder meansare heated, dried if necessary and subjected to dry distillation,thereby to release dry distillation volatiles into a gasification zonesupplied with and containing a bed of gasifiable carbonaceous solidsdownstream of the dry distillation zone and supported on a fire gratedevice, restricting the rate of downward movement of the solids of thebed under gravity in co-current with dry distillation volatiles releasedfrom the dry distillation zone as well as the gasification media and thegenerated fuel gas in the gasification zone flowing through theparticulate solids bed, a supply of oxygen-bearing gases in the drydistillation zone supporting partial combustion therein for heating thedry distillation zone and a supply of gasification medium being providedfor maintaining gasification conditions in the gasification zone by theprovision of feed lines for gasification media to be introduced into theparticulate solids bed which enter into the gasification zone, at leastthe lower region of the bed of gasifiable carbonaceous solids beingmaintained in an embers bed condition through which the dry distillationvolatiles and volatilised products of gasification pass in order to besubjected to thermal cracking and including an ash withdrawal regionincluding a gas separation zone and discharge passage for the generatedfuel gas product and further including additional features adapted forfurther decreasing the content of condensable dry distillation volatilesin the fuel gas product by increasing the intimate contact of the gasesand vapours with the solids beds through which they pass, selected fromeither or both of the following: a) that in relation to higher lyingregions of the gasification zone (5; 5 a; 5 b) the fire grate device(73; 73 a), acting further as a discharge element for the solidsresidues of the gasification, defines a constricted peripheral passage(116; 116 a) for the embers bed of the gasification zone between theouter periphery of the fire grate device (73; 73 a) and the innerperiphery of the exterior walls (82, 85) of the gasification zone, whichconstricted peripheral passage merges into a downwardly and inwardlyfunnel-like sloping constricting pathway (116; 116 a) below the firegrate device leading into and ending with the ash withdrawal region(121; 121 a), where the separation occurs between the ashes and anycinders and the generated fuel gas product; b) that through at least onedry distillation zone solids to be dry-distilled pass in the form of aparticulate solids bed (30) under the action of gravity, wherein furthera gasification medium feed means (3) for an oxygen-containing gas entersbelow the particulate solids bed (2) and wherein for the withdrawal fromthe dry distillation zone of the dry distillation volatiles, formed withheat generation by partial combustion of the solids in the drydistillation reactor, a dry distillation gas duct (4) is connected inthe region of the solids supply means (1) and so enters into agasification zone, that the dry distillation gas flows through theparticulate solids bed (139) in the gasification zone in intimatecontact with and in co-current to the solids material, subject furtherto the condition that, at least when feature a) is absent and where theat least one dry distillation zone, which is designed for theparticulate solids bed therein and the flow of dry distillationvolatiles to pass in counter-current to one another, is to be maintainedin a first vessel distinct and separate from a second vessel, whereinthe bed of carbonaceous solids and gases pass in co-current with oneanother, (i) the first vessel (2) is designed for the bed of particulatesolids to be combusted and gasified substantially entirely to solidsresidues consisting of ashes, cinders and any noncombustible solidscomponents or uncombusted bulky material residues; and (ii) has adischarge locality (22) at its bottom end for the disposal of the solidresidues; and that (iii) the second vessel (5) has its own supply means(6; 68-70) for the introduction, separate from the first vessel (2), ofgasifiable material which is to form the bed of particulate solids inthe second vessel (5), said gas generator including the integers of a),including baffles (118, 119, 118 a, 119 a) defining a meanderingcontinuation of the downwardly and inwardly sloping constrictingpathway, the meandering continuation forming the inlet side to thedischarge passage (123, 128) for generated fuel gas.
 12. Gas generatorfor generating a fuel gas product, including solids feeder meansdischarging into a solids supply portion of a dry distillation zone, inwhich dry distillation zone solids introduced by the solids feeder meansare heated, dried if necessary and subjected to dry distillation,thereby to release dry distillation volatiles into a gasification zonesupplied with and containing a bed of gasifiable carbonaceous solidsdownstream of the dry distillation zone and supported on a fire gratedevice, restricting the rate of downward movement of the solids of thebed under gravity in co-current with dry distillation volatiles releasedfrom the dry distillation zone as well as the gasification media and thegenerated fuel gas in the gasification zone flowing through theparticulate solids bed, a supply of oxygen-bearing gases in the drydistillation zone supporting partial combustion therein for heating thedry distillation zone and a supply of gasification medium being providedfor maintaining gasification conditions in the gasification zone by theprovision of feed lines for gasification media to be introduced into theparticulate solids bed which enter into the gasification zone, at leastthe lower region of the bed of gasifiable carbonaceous solids beingmaintained in an embers bed condition through which the dry distillationvolatiles and volatilised products of gasification pass in order to besubjected to thermal cracking and including an ash withdrawal regionincluding a gas separation zone and discharge passage for the generatedfuel gas product and further including additional features adapted forfurther decreasing the content of condensable dry distillation volatilesin the fuel gas product by increasing the intimate contact of the gasesand vapours with the solids beds through which they pass, selected fromeither or both of the following: a) that in relation to higher lyingregions of the gasification zone (5; 5 a; 5 b) the fire grate device(73; 73 a), acting further as a discharge element for the solidsresidues of the gasification, defines a constricted peripheral passage(116; 116 a) for the embers bed of the gasification zone between theouter periphery of the fire grate device (73; 73 a) and the innerperiphery of the exterior walls (82, 85) of the gasification zone, whichconstricted peripheral passage merges into a downwardly and inwardlyfunnel-like sloping constricting pathway (116; 116 a) below the firegrate device leading into and ending with the ash withdrawal region(121; 121 a), where the separation occurs between the ashes and anycinders and the generated fuel gas product; b) that through at least onedry distillation zone solids to be dry-distilled pass in the form of aparticulate solids bed (30) under the action of gravity, wherein furthera gasification medium feed means (3) for an oxygen-containing gas entersbelow the particulate solids bed (2) and wherein for the withdrawal fromthe dry distillation zone of the dry distillation volatiles, formed withheat generation by partial combustion of the solids in the drydistillation reactor, a dry distillation gas duct (4) is connected inthe region of the solids supply means (1) and so enters into agasification zone, that the dry distillation gas flows through theparticulate solids bed (139) in the gasification zone in intimatecontact with and in co-current to the solids material, subject furtherto the condition that, at least when feature a) is absent and where theat least one dry distillation zone, which is designed for theparticulate solids bed therein and the flow of dry distillationvolatiles to pass in counter-current to one another, is to be maintainedin a first vessel distinct and separate from a second vessel, whereinthe bed of carbonaceous solids and gases pass in co-current with oneanother, (i) the first vessel (2) is designed for the bed of particulatesolids to be combusted and gasified substantially entirely to solidsresidues consisting of ashes, cinders and any non-combustible solidscomponents or uncombusted bulky material residues; and (ii) has adischarge locality (22) at its bottom end for the disposal of the solidresidues; and that (iii) the second vessel (5) has its own supply means(6; 68-70) for the introduction, separate from the first vessel (2), ofgasifiable material which is to form the bed of particulate solids inthe second vessel (5) said gas generator including the integers of a),wherein the fire grate device (73; 73 a) is a rotary fire grate device;wherein the rotary fire grate device (73; 73 a) has a downwardlyconically or pyramidally flaring bed support surface; and wherein therotary fire grate device (73; 73 a) is mounted on a central rotary driveshaft (74; 74 a) which includes a feed passage for oxygen-bearing gasand/or gasifying medium.
 13. Gas generator as claimed in claim 12,wherein the rotary fire grate device includes a vertical succession ofconically or pyramidally flaring bed support surfaces (109, 110; 109 a ,110 a).
 14. Gas generator for generating a fuel gas product, includingsolids feeder means discharging into a solids supply portion of a drydistillation zone, in which dry distillation zone solids introduced bythe solids feeder means are heated, dried if necessary and subjected todry distillation, thereby to release dry distillation volatiles into agasification zone supplied with and containing a bed of gasifiablecarbonaceous solids downstream of the dry distillation zone andsupported on a fire grate device, restricting the rate of downwardmovement of the solids of the bed under gravity in co-current with drydistillation volatiles released from the dry distillation zone as wellas the gasification media and the generated fuel gas in the gasificationzone flowing through the particulate solids bed, a supply ofoxygen-bearing gases in the dry distillation zone supporting partialcombustion therein for heating the dry distillation zone and a supply ofgasification medium being provided for maintaining gasificationconditions in the gasification zone by the provision of feed lines forgasification media to be introduced into the particulate solids bedwhich enter into the gasification zone, at least the lower region of thebed of gasifiable carbonaceous solids being maintained in an embers bedcondition through which the dry distillation volatiles and volatilisedproducts of gasification pass in order to be subjected to thermalcracking and including an ash withdrawal region including a gasseparation zone and discharge passage for the generated fuel gas productand further including additional features adapted for further decreasingthe content of condensable dry distillation volatiles in the fuel gasproduct by increasing the intimate contact of the gases and vapours withthe solids beds through which they pass, selected from either or both ofthe following: a) that in relation to higher lying regions of thegasification zone (5; 5 a; 5 b) the fire grate device (73; 73 a), actingfurther as a discharge element for the solids residues of thegasification, defines a constricted peripheral passage (116; 116 a) forthe embers bed of the gasification zone between the outer periphery ofthe fire grate device (73; 73 a) and the inner periphery of the exteriorwalls (82, 85) of the gasification zone, which constricted peripheralpassage merges into a downwardly and inwardly funnel-like slopingconstricting pathway (116; 116 a) below the fire grate device leadinginto and ending with the ash withdrawal region (121; 121 a), where theseparation occurs between the ashes and any cinders and the generatedfuel gas product; b) that through at least one dry distillation zonesolids to be dry-distilled pass in the form of a particulate solids bed(30) under the action of gravity, wherein further a gasification mediumfeed means (3) for an oxygen-containing gas enters below the particulatesolids bed (2) and wherein for the withdrawal from the dry distillationzone of the dry distillation volatiles, formed with heat generation bypartial combustion of the solids in the dry distillation reactor, a drydistillation gas duct (4) is connected in the region of the solidssupply means (1) and so enters into a gasification zone, that the drydistillation gas flows through the particulate solids bed (139) in thegasification zone in intimate contact with and in co-current to thesolids material, subject further to the condition that, at least whenfeature a) is absent and where the at least one dry distillation zone,which is designed for the particulate solids bed therein and the flow ofdry distillation volatiles to pass in counter-current to one another, isto be maintained in a first vessel distinct and separate from a secondvessel, wherein the bed of carbonaceous solids and gases pass inco-current with one another, (i) the first vessel (2) is designed forthe bed of particulate solids to be combusted and gasified substantiallyentirely to solids residues consisting of ashes, cinders and anynoncombustible solids components or uncombusted bulky material residues;and (ii) has a discharge locality (22) at its bottom end for thedisposal of the solid residues; and that (iii) the second vessel (5) hasits own supply means (6; 68-70) for the introduction, separate from thefirst vessel (2), of gasifiable material which is to form the bed ofparticulate solids in the second vessel (5), said gas generatorincluding the integers of a), wherein the underside of the fire gratedevice (73; 73 a) defining the upper side of the downwardly and inwardlysloping constricted pathway includes formations (122) acting on themovement of the bed in the constricted pathway.
 15. Gas generator forgenerating a fuel gas product, including solids feeder means discharginginto a solids supply portion of a dry distillation zone, in which drydistillation zone solids introduced by the solids feeder means areheated, dried if necessary and subjected to dry distillation, thereby torelease dry distillation volatiles into a gasification zone suppliedwith and containing a bed of gasifiable carbonaceous solids downstreamof the dry distillation zone and supported on a fire grate device,restricting the rate of downward movement of the solids of the bed undergravity in co-current with dry distillation volatiles released from thedry distillation zone as well as the gasification media and thegenerated fuel gas in the gasification zone flowing through theparticulate solids bed, a supply of oxygen-bearing gases in the drydistillation zone supporting partial combustion therein for heating thedry distillation zone and a supply of gasification medium being providedfor maintaining gasification conditions in the gasification zone by theprovision of feed lines for gasification media to be introduced into theparticulate solids bed which enter into the gasification zone, at leastthe lower region of the bed of gasifiable carbonaceous solids beingmaintained in an embers bed condition through which the dry distillationvolatiles and volatilised products of gasification pass in order to besubjected to thermal cracking and including an ash withdrawal regionincluding a gas separation zone and discharge passage for the generatedfuel gas product and further including additional features adapted forfurther decreasing the content of condensable dry distillation volatilesin the fuel gas product by increasing the intimate contact of the gasesand vapours with the solids beds through which they pass, selected fromeither or both of the following: a) that in relation to higher lyingregions of the gasification zone (5; 5 a; 5 b) the fire grate device(73; 73 a), acting further as a discharge element for the solidsresidues of the gasification, defines a constricted peripheral passage(116; 116 a) for the embers bed of the gasification zone between theouter periphery of the fire grate device (73; 73 a) and the innerperiphery of the exterior walls (82, 85) of the gasification zone, whichconstricted peripheral passage merges into a downwardly and inwardlyfunnel-like sloping constricting pathway (116; 116 a) below the firegrate device leading into and ending with the ash withdrawal region(121; 121 a), where the separation occurs between the ashes and anycinders and the generated fuel gas product; b) that through at least onedry distillation zone solids to be dry-distilled pass in the form of aparticulate solids bed (30) under the action of gravity, wherein furthera gasification medium feed means (3) for an oxygen-containing gas entersbelow the particulate solids bed (2) and wherein for the withdrawal fromthe dry distillation zone of the dry distillation volatiles, formed withheat generation by partial combustion of the solids in the drydistillation reactor, a dry distillation gas duct (4) is connected inthe region of the solids supply means (1) and so enters into agasification zone, that the dry distillation gas flows through theparticulate solids bed (139) in the gasification zone in intimatecontact with and in co-current to the solids material, subject furtherto the condition that, at least when feature a) is absent and where theat least one dry distillation zone, which is designed for theparticulate solids bed therein and the flow of dry distillationvolatiles to pass in counter-current to one another, is to be maintainedin a first vessel distinct and separate from a second vessel, whereinthe bed of carbonaceous solids and gases pass in co-current with oneanother, (i) the first vessel (2) is designed for the bed of particulatesolids to be combusted and gasified substantially entirely to solidsresidues consisting of ashes, cinders and any non-combustible solidscomponents or uncombusted bulky material residues; and (ii) has adischarge locality (22) at its bottom end for the disposal of the solidresidues; and that (iii) the second vessel (5) has its own supply means(6; 68-70) for the introduction, separate from the first vessel (2), ofgasifiable material which is to form the bed of particulate solids inthe second vessel (5), said gas generator including the integers of a),wherein the fire grate device (73; 73 a) and solids discharge elementincludes a hollow conical or pyramidal body (109; 109 a) connected to asupply (104, 99) of gasifying medium and having gasifying medium outletformations (103) on its underside (113) leading into a region of thegasification zone where gasification conditions are to be maintained.16. Gas generator as claimed in claim 15, wherein the rotary fire gratedevice includes a vertical succession of conically or pyramidallyflaring bed support surfaces (109, 110; 109 a , 110 a) and wherein theunderside of the hollow conical or pyramidal body (110; 110 a)communicates with the apex region of a further hollow conical orpyramidal body (109; 109 a), through which the gasification medium is tobe supplied.
 17. Gas generator for generating a fuel gas product,including solids feeder means discharging into a solids supply portionof a dry distillation zone, in which dry distillation zone solidsintroduced by the solids feeder means are heated, dried if necessary andsubjected to dry distillation, thereby to release dry distillationvolatiles into a gasification zone supplied with and containing a bed ofgasifiable carbonaceous solids downstream of the dry distillation zoneand supported on a fire grate device, restricting the rate of downwardmovement of the solids of the bed under gravity in co-current with drydistillation volatiles released from the dry distillation zone as wellas the gasification media and the generated fuel gas in the gasificationzone flowing through the particulate solids bed, a supply ofoxygen-bearing gases in the dry distillation zone supporting partialcombustion therein for heating the dry distillation zone and a supply ofgasification medium being provided for maintaining gasificationconditions in the gasification zone by the provision of feed lines forgasification media to be introduced into the particulate solids bedwhich enter into the gasification zone, at least the lower region of thebed of gasifiable carbonaceous solids being maintained in an embers bedcondition through which the dry distillation volatiles and volatilisedproducts of gasification pass in order to be subjected to thermalcracking and including an ash withdrawal region including a gasseparation zone and discharge passage for the generated fuel gas productand further including additional features adapted for further decreasingthe content of condensable dry distillation volatiles in the fuel gasproduct by increasing the intimate contact of the gases and vapours withthe solids beds through which they pass, selected from either or both ofthe following: a) that in relation to higher lying regions of thegasification zone (5; 5 a; 5 b) the fire grate device (73; 73 a), actingfurther as a discharge element for the solids residues of thegasification, defines a constricted peripheral passage (116; 116 a) forthe embers bed of the gasification zone between the outer periphery ofthe fire grate device (73; 73 a) and the inner periphery of the exteriorwalls (82, 85) of the gasification zone, which constricted peripheralpassage merges into a downwardly and inwardly funnel-like slopingconstricting pathway (116; 116 a) below the fire grate device leadinginto and ending with the ash withdrawal region (121; 121 a), where theseparation occurs between the ashes and any cinders and the generatedfuel gas product; b) that through at least one dry distillation zonesolids to be dry-distilled pass in the form of a particulate solids bed(30) under the action of gravity, wherein further a gasification mediumfeed means (3) for an oxygen-containing gas enters below the particulatesolids bed (2) and wherein for the withdrawal from the dry distillationzone of the dry distillation volatiles, formed with heat generation bypartial combustion of the solids in the dry distillation reactor, a drydistillation gas duct (4) is connected in the region of the solidssupply means (1) and so enters into a gasification zone, that the drydistillation gas flows through the particulate solids bed (139) in thegasification zone in intimate contact with and in co-current to thesolids material, subject further to the condition that, at least whenfeature a) is absent and where the at least one dry distillation zone,which is designed for the particulate solids bed therein and the flow ofdry distillation volatiles to pass in counter-current to one another, isto be maintained in a first vessel distinct and separate from a secondvessel, wherein the bed of carbonaceous solids and gases pass inco-current with one another, (i) the first vessel (2) is designed forthe bed of particulate solids to be combusted and gasified substantiallyentirely to solids residues consisting of ashes, cinders and anynon-combustible solids components or uncombusted bulky materialresidues; and (ii) has a discharge locality (22) at its bottom end forthe disposal of the solid residues; and that (iii) the second vessel (5)has its own supply means (6; 68-70) for the introduction, separate fromthe first vessel (2), of gasifiable material which is to form the bed ofparticulate solids in the second vessel (5), and wherein in thedischarge region of the gasification zone for the discharge of thesolids residues a baffle device (118, 119; 118 a, 119 a) is provided insuch a manner that the discharge of solids residues is limited to amaximum solids particle size and/or to a limited discharge rate andwherein for the separation of solids residues to be discharged and fuelgas to be released, a gas passage formation (124; 130) is provided,guiding the fuel gas out of the solids residues bed along a meanderingpathway (130, 130 a, 130 b).
 18. Gas generator for generating a fuel gasproduct, including solids feeder means discharging into a solids supplyportion of a dry distillation zone, in which dry distillation zonesolids introduced by the solids feeder means are heated, dried ifnecessary and subjected to dry distillation, thereby to release drydistillation volatiles into a gasification zone supplied with andcontaining a bed of gasifiable carbonaceous solids downstream of the drydistillation zone and supported on a fire grate device, restricting therate of downward movement of the solids of the bed under gravity inco-current with dry distillation volatiles released from the drydistillation zone as well as the gasification media and the generatedfuel gas in the gasification zone flowing through the particulate solidsbed, a supply of oxygen-bearing gases in the dry distillation zonesupporting partial combustion therein for heating the dry distillationzone and a supply of gasification medium being provided for maintaininggasification conditions in the gasification zone by the provision offeed lines for gasification media to be introduced into the particulatesolids bed which enter into the gasification zone, at least the lowerregion of the bed of gasifiable carbonaceous solids being maintained inan embers bed condition through which the dry distillation volatiles andvolatilised products of gasification pass in order to be subjected tothermal cracking and including an ash withdrawal region including a gasseparation zone and discharge passage for the generated fuel gas productand further including additional features adapted for further decreasingthe content of condensable dry distillation volatiles in the fuel gasproduct by increasing the intimate contact of the gases and vapours withthe solids beds through which they pass, selected from either or both ofthe following: a) that in relation to higher lying regions of thegasification zone (5; 5 a; 5 b) the fire grate device (73; 73 a), actingfurther as a discharge element for the solids residues of thegasification, defines a constricted peripheral passage (116; 116 a) forthe embers bed of the gasification zone between the outer periphery ofthe fire grate device (73; 73 a) and the inner periphery of the exteriorwalls (82, 85) of the gasification zone, which constricted peripheralpassage merges into a downwardly and inwardly funnel-like slopingconstricting pathway (116; 116 a) below the fire grate device leadinginto and ending with the ash withdrawal region (121; 121 a), where theseparation occurs between the ashes and any cinders and the generatedfuel gas product; b) that through at least one dry distillation zonesolids to be dry-distilled pass in the form of a particulate solids bed(30) under the action of gravity, wherein further a gasification mediumfeed means (3) for an oxygen-containing gas enters below the particulatesolids bed (2) and wherein for the withdrawal from the dry distillationzone of the dry distillation volatiles, formed with heat generation bypartial combustion of the solids in the dry distillation reactor, a drydistillation gas duct (4) is connected in the region of the solidssupply means (1) and so enters into a gasification zone, that the drydistillation gas flows through the particulate solids bed (139) in thegasification zone in intimate contact with and in co-current to thesolids material, subject further to the condition that, at least whenfeature a) is absent and where the at least one dry distillation zone,which is designed for the particulate solids bed therein and the flow ofdry distillation volatiles to pass in counter-current to one another, isto be maintained in a first vessel distinct and separate from a secondvessel, wherein the bed of carbonaceous solids and gases pass inco-current with one another, (i) the first vessel (2) is designed forthe bed of particulate solids to be combusted and gasified substantiallyentirely to solids residues consisting of ashes, cinders and anynon-combustible solids components or uncombusted bulky materialresidues; and (ii) has a discharge locality (22) at its bottom end forthe disposal of the solid residues; and that (iii) the second vessel (5)has its own supply means (6; 68-70) for the introduction, separate fromthe first vessel (2), of gasifiable material which is to form the bed ofparticulate solids in the second vessel (5), said gas generatorincluding the integers of a), wherein the discharge element (73; 73 a)is fitted to a drive shaft (74; 74 a) which is rotatable in theparticulate solids bed, and wherein the drive shaft (74; 74 a) of thedischarge element in the gasification reactor is designed as a hollowshaft and serves as a gas duct.
 19. Gas generator for generating a fuelgas product, including solids feeder means discharging into a solidssupply portion of a dry distillation zone, in which dry distillationzone solids introduced by the solids feeder means are heated, dried ifnecessary and subjected to dry distillation, thereby to release drydistillation volatiles into a gasification zone supplied with andcontaining a bed of gasifiable carbonaceous solids downstream of the drydistillation zone and supported on a fire grate device, restricting therate of downward movement of the solids of the bed under gravity inco-current with dry distillation volatiles released from the drydistillation zone as well as the gasification media and the generatedfuel gas in the gasification zone flowing through the particulate solidsbed, a supply of oxygen-bearing gases in the dry distillation zonesupporting partial combustion therein for heating the dry distillationzone and a supply of gasification medium being provided for maintaininggasification conditions in the gasification zone by the provision offeed lines for gasification media to be introduced into the particulatesolids bed which enter into the gasification zone, at least the lowerregion of the bed of gasifiable carbonaceous solids being maintained inan embers bed condition through which the dry distillation volatiles andvolatilised products of gasification pass in order to be subjected tothermal cracking and including an ash withdrawal region including a gasseparation zone and discharge passage for the generated fuel gas productand further including additional features adapted for further decreasingthe content of condensable dry distillation volatiles in the fuel gasproduct by increasing the intimate contact of the gases and vapours withthe solids beds through which they pass, selected from either or both ofthe following: a) that in relation to higher lying regions of thegasification zone (5; 5 a; 5 b) the fire grate device (73; 73 a), actingfurther as a discharge element for the solids residues of thegasification, defines a constricted peripheral passage (116; 116 a) forthe embers bed of the gasification zone between the outer periphery ofthe fire grate device (73; 73 a) and the inner periphery of the exteriorwalls (82, 85) of the gasification zone, which constricted peripheralpassage merges into a downwardly and inwardly funnel-like slopingconstricting pathway (116; 116 a) below the fire grate device leadinginto and ending with the ash withdrawal region (121; 121 a), where theseparation occurs between the ashes and any cinders and the generatedfuel gas product; b) that through at least one dry distillation zonesolids to be dry-distilled pass in the form of a particulate solids bed(30) under the action of gravity, wherein further a gasification mediumfeed means (3) for an oxygen-containing gas enters below the particulatesolids bed (2) and wherein for the withdrawal from the dry distillationzone of the dry distillation volatiles, formed with heat generation bypartial combustion of the solids in the dry distillation reactor, a drydistillation gas duct (4) is connected in the region of the solidssupply means (1) and so enters into a gasification zone, that the drydistillation gas flows through the particulate solids bed (139) in thegasification zone in intimate contact with and in co-current to thesolids material, subject further to the condition that, at least whenfeature a) is absent and where the at least one dry distillation zone,which is designed for the particulate solids bed therein and the flow ofdry distillation volatiles to pass in counter-current to one another, isto be maintained in a first vessel distinct and separate from a secondvessel, wherein the bed of carbonaceous solids and gases pass inco-current with one another, (i) the first vessel (2) is designed forthe bed of particulate solids to be combusted and gasified substantiallyentirely to solids residues consisting of ashes, cinders and anynon-combustible solids components or uncombusted bulky materialresidues; and (ii) has a discharge locality (22) at its bottom end forthe disposal of the solid residues; and that (iii) the second vessel (5)has its own supply means (6; 68-70) for the introduction, separate fromthe first vessel (2), of gasifiable material which is to form the bed ofparticulate solids in the second vessel (5), wherein at least part ofthe dry distillation zone (2) is accommodated in a first reactor vessel(26) separate from a second reactor vessel (71) accommodating thegasification zone (5), and a duct or passage (4) is provided for feedingdry distillation volatiles from the first vessel into the second vesseland wherein the first reactor vessel (26) includes a solids feeder (27,28, 29) means discharging into a solids supply portion of a drydistillation zone, in which dry distillation zone solids introduced bythe solids feeder means are heated, dried if necessary and subjected todry distillation, thereby to release dry distillation volatiles and afire grate device, between which and the solids feeder a drydistillation zone (2) is situated, and feed means (3) foroxygen-containing gas enter into a lower region of the dry distillationzone (2) from where partial combustion conditions are to be created, aswell as gas withdrawal ducts connected to the upper region of the drydistillation zone (2); and wherein the duct or passage (4) for feedingdry distillation volatiles from the first reactor vessel (26) into thesecond reactor vessel (71) enter the second vessel in an upper region(96) of the second reactor vessel.
 20. Gas generator for generating afuel gas product, including solids feeder means discharging into asolids supply portion of a dry distillation zone, in which drydistillation zone solids introduced by the solids feeder means areheated, dried if necessary and subjected to dry distillation, thereby torelease dry distillation volatiles into a gasification zone suppliedwith and containing a bed of gasifiable carbonaceous solids downstreamof the dry distillation zone and supported on a fire grate device,restricting the rate of downward movement of the solids of the bed undergravity in co-current with dry distillation volatiles released from thedry distillation zone as well as the gasification media and thegenerated fuel gas in the gasification zone flowing through theparticulate solids bed, a supply of oxygen-bearing gases in the drydistillation zone supporting partial combustion therein for heating thedry distillation zone and a supply of gasification medium being providedfor maintaining gasification conditions in the gasification zone by theprovision of feed lines for gasification media to be introduced into theparticulate solids bed which enter into the gasification zone, at leastthe lower region of the bed of gasifiable carbonaceous solids beingmaintained in an embers bed condition through which the dry distillationvolatiles and volatilised products of gasification pass in order to besubjected to thermal cracking and including an ash withdrawal regionincluding a gas separation zone and discharge passage for the generatedfuel gas product and further including additional features adapted forfurther decreasing the content of condensable dry distillation volatilesin the fuel gas product by increasing the intimate contact of the gasesand vapours with the solids beds through which they pass, selected fromeither or both of the following: a) that in relation to higher lyingregions of the gasification zone (5; 5 a; 5 b) the fire grate device(73; 73 a), acting further as a discharge element for the solidsresidues of the gasification, defines a constricted peripheral passage(116; 116 a) for the embers bed of the gasification zone between theouter periphery of the fire grate device (73; 73 a) and the innerperiphery of the exterior walls (82, 85) of the gasification zone, whichconstricted peripheral passage merges into a downwardly and inwardlyfunnel-like sloping constricting pathway (116; 116 a) below the firegrate device leading into and ending with the ash withdrawal region(121; 121 a), where the separation occurs between the ashes and anycinders and the generated fuel gas product; b) that through at least onedry distillation zone solids to be dry-distilled pass in the form of aparticulate solids bed (30) under the action of gravity, wherein furthera gasification medium feed means (3) for an oxygen-containing gas entersbelow the particulate solids bed (2) and wherein for the withdrawal fromthe dry distillation zone of the dry distillation volatiles, formed withheat generation by partial combustion of the solids in the drydistillation reactor, a dry distillation gas duct (4) is connected inthe region of the solids supply means (1) and so enters into agasification zone, that the dry distillation gas flows through theparticulate solids bed (139) in the gasification zone in intimatecontact with and in co-current to the solids material, subject furtherto the condition that, at least when feature a) is absent and where theat least one dry distillation zone, which is designed for theparticulate solids bed therein and the flow of dry distillationvolatiles to pass in counter-current to one another, is to be maintainedin a first vessel distinct and separate from a second vessel, whereinthe bed of carbonaceous solids and gases pass in co-current with oneanother, (i) the first vessel (2) is designed for the bed of particulatesolids to be combusted and gasified substantially entirely to solidsresidues consisting of ashes, cinders and any non-combustible solidscomponents or uncombusted bulky material residues; and (ii) has adischarge locality (22) at its bottom end for the disposal of the solidresidues; and that (iii) the second vessel (5) has its own supply means(6; 68-70) for the introduction, separate from the first vessel (2), ofgasifiable material which is to form the bed of particulate solids inthe second vessel (5), said gas generator including a cylindrical shaftreactor and a coaxial drive shaft (74; 74 a; 74 b) carrying a rotaryfire grate and/or bed support and/or bed agitation/reconstitution meansand discharge element (73; 73 a; 73 b), including an inlet (276) foroxygen-containing gas near the top (273) of the solids supply region(271, 272) of the cylindrical shaft reactor (5 b) and including a supplypipe (274) for oxygen-containing gas surrounding the drive shaft (74; 74a; 74 b) forming a gas passage leading from near the said top (273) downinto an upper partial combustion region of the solids bed.
 21. Gasgenerator as claimed in claim 20, wherein the lower end of the supplypipe (274) is associated with a further rotary bed agitating member(278).